From 01c62f86b35b39666c250fbc4a319579af450db5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?St=C3=A9phane=20Nicoll?= <stephane.nicoll@broadcom.com>
Date: Sun, 7 Jan 2024 16:58:28 +0100
Subject: [PATCH] Polish

---
 .../messaging/MessageHeadersTests.java        | 46 ++++++-------
 .../DefaultContentTypeResolverTests.java      | 18 ++---
 .../GenericMessageConverterTests.java         | 10 +--
 .../converter/GsonMessageConverterTests.java  | 26 ++++----
 .../converter/JsonbMessageConverterTests.java | 26 ++++----
 .../MappingJackson2MessageConverterTests.java | 22 +++----
 .../MarshallingMessageConverterTests.java     | 15 ++---
 .../converter/MessageConverterTests.java      | 24 +++----
 .../SimpleMessageConverterTests.java          | 10 +--
 .../StringMessageConverterTests.java          | 20 +++---
 .../core/CachingDestinationResolverTests.java | 11 ++--
 ...nationResolvingMessagingTemplateTests.java | 34 +++++-----
 .../core/GenericMessagingTemplateTests.java   | 23 ++++---
 .../core/MessageReceivingTemplateTests.java   | 20 +++---
 .../MessageRequestReplyTemplateTests.java     | 26 ++++----
 .../core/MessageSendingTemplateTests.java     | 32 ++++-----
 ...tinationPatternsMessageConditionTests.java | 34 +++++-----
 ...essageMappingReflectiveProcessorTests.java |  4 +-
 ...onVariableMethodArgumentResolverTests.java | 10 +--
 .../HeaderMethodArgumentResolverTests.java    | 23 ++++---
 .../HeadersMethodArgumentResolverTests.java   | 15 ++---
 .../MessageMappingMessageHandlerTests.java    | 18 ++---
 .../PayloadMethodArgumentResolverTests.java   | 20 +++---
 ...onExceptionHandlerMethodResolverTests.java | 24 +++----
 ...faultMessageHandlerMethodFactoryTests.java | 18 ++---
 ...onVariableMethodArgumentResolverTests.java | 10 +--
 .../HeaderMethodArgumentResolverTests.java    | 23 ++++---
 .../HeadersMethodArgumentResolverTests.java   | 16 ++---
 .../MessageMethodArgumentResolverTests.java   | 34 +++++-----
 .../PayloadMethodArgumentResolverTests.java   | 34 +++++-----
 .../InvocableHandlerMethodTests.java          | 22 +++----
 .../invocation/MethodMessageHandlerTests.java | 24 ++++---
 .../EncoderMethodReturnValueHandlerTests.java | 16 ++---
 .../reactive/InvocableHandlerMethodTests.java | 24 +++----
 .../reactive/MethodMessageHandlerTests.java   |  8 +--
 .../DefaultMetadataExtractorTests.java        |  4 +-
 .../DefaultRSocketRequesterBuilderTests.java  | 21 +++---
 .../rsocket/DefaultRSocketRequesterTests.java | 28 ++++----
 .../DefaultRSocketStrategiesTests.java        |  3 +-
 .../LeakAwareNettyDataBufferFactory.java      |  4 +-
 .../rsocket/MetadataEncoderTests.java         |  4 +-
 .../messaging/rsocket/PayloadUtilsTests.java  |  4 +-
 .../rsocket/RSocketBufferLeakTests.java       |  4 +-
 ...RSocketClientToServerIntegrationTests.java | 26 ++++----
 ...RSocketServerToClientIntegrationTests.java |  4 +-
 ...RSocketFrameTypeMessageConditionTests.java | 12 ++--
 .../support/RSocketMessageHandlerTests.java   | 22 +++----
 ...tinationVariableArgumentResolverTests.java |  4 +-
 .../MetadataArgumentResolverTests.java        |  4 +-
 .../service/PayloadArgumentResolverTests.java |  4 +-
 .../service/RSocketRequestValuesTests.java    |  4 +-
 .../service/RSocketServiceMethodTests.java    |  6 +-
 .../SimpAttributesContextHolderTests.java     | 24 +++----
 .../messaging/simp/SimpAttributesTests.java   | 22 +++----
 .../simp/SimpMessageHeaderAccessorTests.java  | 16 ++---
 .../SimpMessageTypeMessageConditionTests.java | 12 ++--
 .../simp/SimpMessagingTemplateTests.java      | 31 +++++----
 .../messaging/simp/SimpSessionScopeTests.java | 18 ++---
 .../PrincipalMethodArgumentResolverTests.java |  8 +--
 .../SendToMethodReturnValueHandlerTests.java  | 46 ++++++-------
 ...mpAnnotationMethodMessageHandlerTests.java | 40 ++++++------
 ...criptionMethodReturnValueHandlerTests.java | 10 +--
 .../broker/BrokerMessageHandlerTests.java     | 24 +++----
 .../DefaultSubscriptionRegistryTests.java     |  8 +--
 .../OrderedMessageChannelDecoratorTests.java  | 10 +--
 .../SimpleBrokerMessageHandlerTests.java      | 22 +++----
 .../MessageBrokerConfigurationTests.java      | 52 +++++++--------
 .../StompBrokerRelayRegistrationTests.java    |  6 +-
 ...tractStompBrokerRelayIntegrationTests.java | 20 +++---
 .../stomp/BufferingStompDecoderTests.java     | 28 ++++----
 .../simp/stomp/DefaultStompSessionTests.java  | 65 +++++++++----------
 ...NettyStompBrokerRelayIntegrationTests.java |  4 +-
 .../ReactorNettyTcpStompClientTests.java      | 12 ++--
 .../simp/stomp/StompClientSupportTests.java   | 14 ++--
 .../simp/stomp/StompCommandTests.java         | 14 ++--
 .../simp/stomp/StompDecoderTests.java         | 42 ++++++------
 .../simp/stomp/StompEncoderTests.java         | 14 ++--
 .../simp/stomp/StompHeaderAccessorTests.java  | 61 +++++++++--------
 .../DefaultUserDestinationResolverTests.java  | 50 ++++++--------
 .../user/UserRegistryMessageHandlerTests.java | 14 ++--
 .../support/ChannelInterceptorTests.java      | 18 ++---
 .../messaging/support/ErrorMessageTests.java  |  6 +-
 .../ExecutorSubscribableChannelTests.java     | 22 +++----
 .../support/MessageBuilderTests.java          | 10 +--
 .../support/MessageHeaderAccessorTests.java   | 54 +++++++--------
 .../NativeMessageHeaderAccessorTests.java     | 34 +++++-----
 86 files changed, 853 insertions(+), 876 deletions(-)

diff --git a/spring-messaging/src/test/java/org/springframework/messaging/MessageHeadersTests.java b/spring-messaging/src/test/java/org/springframework/messaging/MessageHeadersTests.java
index 9820f51548..a5274b26d8 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/MessageHeadersTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/MessageHeadersTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,16 +36,16 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  * @author Gary Russell
  * @author Juergen Hoeller
  */
-public class MessageHeadersTests {
+class MessageHeadersTests {
 
 	@Test
-	public void testTimestamp() {
+	void testTimestamp() {
 		MessageHeaders headers = new MessageHeaders(null);
 		assertThat(headers.getTimestamp()).isNotNull();
 	}
 
 	@Test
-	public void testTimestampOverwritten() throws Exception {
+	void testTimestampOverwritten() throws Exception {
 		MessageHeaders headers1 = new MessageHeaders(null);
 		Thread.sleep(50L);
 		MessageHeaders headers2 = new MessageHeaders(headers1);
@@ -53,59 +53,59 @@ public class MessageHeadersTests {
 	}
 
 	@Test
-	public void testTimestampProvided() throws Exception {
+	void testTimestampProvided() {
 		MessageHeaders headers = new MessageHeaders(null, null, 10L);
 		assertThat(headers.getTimestamp()).isEqualTo(10L);
 	}
 
 	@Test
-	public void testTimestampProvidedNullValue() throws Exception {
-		Map<String, Object> input = Collections.<String, Object>singletonMap(MessageHeaders.TIMESTAMP, 1L);
+	void testTimestampProvidedNullValue() {
+		Map<String, Object> input = Collections.singletonMap(MessageHeaders.TIMESTAMP, 1L);
 		MessageHeaders headers = new MessageHeaders(input, null, null);
 		assertThat(headers.getTimestamp()).isNotNull();
 	}
 
 	@Test
-	public void testTimestampNone() throws Exception {
+	void testTimestampNone() {
 		MessageHeaders headers = new MessageHeaders(null, null, -1L);
 		assertThat(headers.getTimestamp()).isNull();
 	}
 
 	@Test
-	public void testIdOverwritten() throws Exception {
+	void testIdOverwritten() {
 		MessageHeaders headers1 = new MessageHeaders(null);
 		MessageHeaders headers2 = new MessageHeaders(headers1);
 		assertThat(headers2.getId()).isNotSameAs(headers1.getId());
 	}
 
 	@Test
-	public void testId() {
+	void testId() {
 		MessageHeaders headers = new MessageHeaders(null);
 		assertThat(headers.getId()).isNotNull();
 	}
 
 	@Test
-	public void testIdProvided() {
+	void testIdProvided() {
 		UUID id = new UUID(0L, 25L);
 		MessageHeaders headers = new MessageHeaders(null, id, null);
 		assertThat(headers.getId()).isEqualTo(id);
 	}
 
 	@Test
-	public void testIdProvidedNullValue() {
-		Map<String, Object> input = Collections.<String, Object>singletonMap(MessageHeaders.ID, new UUID(0L, 25L));
+	void testIdProvidedNullValue() {
+		Map<String, Object> input = Collections.singletonMap(MessageHeaders.ID, new UUID(0L, 25L));
 		MessageHeaders headers = new MessageHeaders(input, null, null);
 		assertThat(headers.getId()).isNotNull();
 	}
 
 	@Test
-	public void testIdNone() {
+	void testIdNone() {
 		MessageHeaders headers = new MessageHeaders(null, MessageHeaders.ID_VALUE_NONE, null);
 		assertThat(headers.getId()).isNull();
 	}
 
 	@Test
-	public void testNonTypedAccessOfHeaderValue() {
+	void testNonTypedAccessOfHeaderValue() {
 		Integer value = 123;
 		Map<String, Object> map = new HashMap<>();
 		map.put("test", value);
@@ -114,7 +114,7 @@ public class MessageHeadersTests {
 	}
 
 	@Test
-	public void testTypedAccessOfHeaderValue() {
+	void testTypedAccessOfHeaderValue() {
 		Integer value = 123;
 		Map<String, Object> map = new HashMap<>();
 		map.put("test", value);
@@ -123,7 +123,7 @@ public class MessageHeadersTests {
 	}
 
 	@Test
-	public void testHeaderValueAccessWithIncorrectType() {
+	void testHeaderValueAccessWithIncorrectType() {
 		Integer value = 123;
 		Map<String, Object> map = new HashMap<>();
 		map.put("test", value);
@@ -133,21 +133,21 @@ public class MessageHeadersTests {
 	}
 
 	@Test
-	public void testNullHeaderValue() {
+	void testNullHeaderValue() {
 		Map<String, Object> map = new HashMap<>();
 		MessageHeaders headers = new MessageHeaders(map);
 		assertThat(headers.get("nosuchattribute")).isNull();
 	}
 
 	@Test
-	public void testNullHeaderValueWithTypedAccess() {
+	void testNullHeaderValueWithTypedAccess() {
 		Map<String, Object> map = new HashMap<>();
 		MessageHeaders headers = new MessageHeaders(map);
 		assertThat(headers.get("nosuchattribute", String.class)).isNull();
 	}
 
 	@Test
-	public void testHeaderKeys() {
+	void testHeaderKeys() {
 		Map<String, Object> map = new HashMap<>();
 		map.put("key1", "val1");
 		map.put("key2", 123);
@@ -156,7 +156,7 @@ public class MessageHeadersTests {
 	}
 
 	@Test
-	public void serializeWithAllSerializableHeaders() throws Exception {
+	void serializeWithAllSerializableHeaders() throws Exception {
 		Map<String, Object> map = new HashMap<>();
 		map.put("name", "joe");
 		map.put("age", 42);
@@ -169,7 +169,7 @@ public class MessageHeadersTests {
 	}
 
 	@Test
-	public void serializeWithNonSerializableHeader() throws Exception {
+	void serializeWithNonSerializableHeader() throws Exception {
 		Object address = new Object();
 		Map<String, Object> map = new HashMap<>();
 		map.put("name", "joe");
@@ -183,7 +183,7 @@ public class MessageHeadersTests {
 	}
 
 	@Test
-	public void subclassWithCustomIdAndNoTimestamp() {
+	void subclassWithCustomIdAndNoTimestamp() {
 		final AtomicLong id = new AtomicLong();
 		@SuppressWarnings("serial")
 		class MyMH extends MessageHeaders {
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/converter/DefaultContentTypeResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/converter/DefaultContentTypeResolverTests.java
index d9c335be3e..2fa284cd59 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/converter/DefaultContentTypeResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/converter/DefaultContentTypeResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,43 +35,43 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  *
  * @author Rossen Stoyanchev
  */
-public class DefaultContentTypeResolverTests {
+class DefaultContentTypeResolverTests {
 
 	private final DefaultContentTypeResolver resolver = new DefaultContentTypeResolver();
 
 
 	@Test
-	public void resolve() {
+	void resolve() {
 		MessageHeaders headers = headers(MimeTypeUtils.APPLICATION_JSON);
 		assertThat(this.resolver.resolve(headers)).isEqualTo(MimeTypeUtils.APPLICATION_JSON);
 	}
 
 	@Test
-	public void resolveStringContentType() {
+	void resolveStringContentType() {
 		MessageHeaders headers = headers(MimeTypeUtils.APPLICATION_JSON_VALUE);
 		assertThat(this.resolver.resolve(headers)).isEqualTo(MimeTypeUtils.APPLICATION_JSON);
 	}
 
 	@Test
-	public void resolveInvalidStringContentType() {
+	void resolveInvalidStringContentType() {
 		MessageHeaders headers = headers("invalidContentType");
 		assertThatExceptionOfType(InvalidMimeTypeException.class).isThrownBy(() -> this.resolver.resolve(headers));
 	}
 
 	@Test
-	public void resolveUnknownHeaderType() {
+	void resolveUnknownHeaderType() {
 		MessageHeaders headers = headers(1);
 		assertThatIllegalArgumentException().isThrownBy(() -> this.resolver.resolve(headers));
 	}
 
 	@Test
-	public void resolveNoContentTypeHeader() {
+	void resolveNoContentTypeHeader() {
 		MessageHeaders headers = new MessageHeaders(Collections.emptyMap());
 		assertThat(this.resolver.resolve(headers)).isNull();
 	}
 
 	@Test
-	public void resolveDefaultMimeType() {
+	void resolveDefaultMimeType() {
 		this.resolver.setDefaultMimeType(MimeTypeUtils.APPLICATION_JSON);
 		MessageHeaders headers = new MessageHeaders(Collections.emptyMap());
 
@@ -79,7 +79,7 @@ public class DefaultContentTypeResolverTests {
 	}
 
 	@Test
-	public void resolveDefaultMimeTypeWithNoHeader() {
+	void resolveDefaultMimeTypeWithNoHeader() {
 		this.resolver.setDefaultMimeType(MimeTypeUtils.APPLICATION_JSON);
 		assertThat(this.resolver.resolve(null)).isEqualTo(MimeTypeUtils.APPLICATION_JSON);
 	}
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/converter/GenericMessageConverterTests.java b/spring-messaging/src/test/java/org/springframework/messaging/converter/GenericMessageConverterTests.java
index 1e39544a78..244947b624 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/converter/GenericMessageConverterTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/converter/GenericMessageConverterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,25 +33,25 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
  *
  * @author Stephane Nicoll
  */
-public class GenericMessageConverterTests {
+class GenericMessageConverterTests {
 
 	private final ConversionService conversionService = new DefaultConversionService();
 	private final GenericMessageConverter converter = new GenericMessageConverter(conversionService);
 
 	@Test
-	public void fromMessageWithConversion() {
+	void fromMessageWithConversion() {
 		Message<String> content = MessageBuilder.withPayload("33").build();
 		assertThat(converter.fromMessage(content, Integer.class)).isEqualTo(33);
 	}
 
 	@Test
-	public void fromMessageNoConverter() {
+	void fromMessageNoConverter() {
 		Message<Integer> content = MessageBuilder.withPayload(1234).build();
 		assertThat(converter.fromMessage(content, Locale.class)).as("No converter from integer to locale").isNull();
 	}
 
 	@Test
-	public void fromMessageWithFailedConversion() {
+	void fromMessageWithFailedConversion() {
 		Message<String> content = MessageBuilder.withPayload("test not a number").build();
 		assertThatExceptionOfType(MessageConversionException.class).isThrownBy(() ->
 				converter.fromMessage(content, Integer.class))
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/converter/GsonMessageConverterTests.java b/spring-messaging/src/test/java/org/springframework/messaging/converter/GsonMessageConverterTests.java
index 2c67e9cc6f..30e4890e09 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/converter/GsonMessageConverterTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/converter/GsonMessageConverterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,16 +41,16 @@ import static org.assertj.core.api.Assertions.within;
  * @author Rossen Stoyanchev
  * @author Sebastien Deleuze
  */
-public class GsonMessageConverterTests {
+class GsonMessageConverterTests {
 
 	@Test
-	public void defaultConstructor() {
+	void defaultConstructor() {
 		GsonMessageConverter converter = new GsonMessageConverter();
 		assertThat(converter.getSupportedMimeTypes()).contains(new MimeType("application", "json"));
 	}
 
 	@Test
-	public void fromMessage() {
+	void fromMessage() {
 		GsonMessageConverter converter = new GsonMessageConverter();
 		String payload = "{\"array\":[\"Foo\",\"Bar\"]," +
 				"\"number\":42,\"string\":\"Foo\",\"bool\":true,\"fraction\":42.0}";
@@ -65,7 +65,7 @@ public class GsonMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageUntyped() {
+	void fromMessageUntyped() {
 		GsonMessageConverter converter = new GsonMessageConverter();
 		String payload = "{\"array\":[\"Foo\",\"Bar\"]," +
 				"\"number\":42,\"string\":\"Foo\",\"bool\":true,\"fraction\":42.0}";
@@ -81,7 +81,7 @@ public class GsonMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageMatchingInstance() {
+	void fromMessageMatchingInstance() {
 		MyBean myBean = new MyBean();
 		GsonMessageConverter converter = new GsonMessageConverter();
 		Message<?> message = MessageBuilder.withPayload(myBean).build();
@@ -89,7 +89,7 @@ public class GsonMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageInvalidJson() {
+	void fromMessageInvalidJson() {
 		GsonMessageConverter converter = new GsonMessageConverter();
 		String payload = "FooBar";
 		Message<?> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
@@ -98,7 +98,7 @@ public class GsonMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageValidJsonWithUnknownProperty() {
+	void fromMessageValidJsonWithUnknownProperty() {
 		GsonMessageConverter converter = new GsonMessageConverter();
 		String payload = "{\"string\":\"string\",\"unknownProperty\":\"value\"}";
 		Message<?> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
@@ -107,7 +107,7 @@ public class GsonMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageToList() throws Exception {
+	void fromMessageToList() throws Exception {
 		GsonMessageConverter converter = new GsonMessageConverter();
 		String payload = "[1, 2, 3, 4, 5, 6, 7, 8, 9]";
 		Message<?> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
@@ -121,7 +121,7 @@ public class GsonMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageToMessageWithPojo() throws Exception {
+	void fromMessageToMessageWithPojo() throws Exception {
 		GsonMessageConverter converter = new GsonMessageConverter();
 		String payload = "{\"string\":\"foo\"}";
 		Message<?> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
@@ -135,7 +135,7 @@ public class GsonMessageConverterTests {
 	}
 
 	@Test
-	public void toMessage() {
+	void toMessage() {
 		GsonMessageConverter converter = new GsonMessageConverter();
 		MyBean payload = new MyBean();
 		payload.setString("Foo");
@@ -156,7 +156,7 @@ public class GsonMessageConverterTests {
 	}
 
 	@Test
-	public void toMessageUtf16() {
+	void toMessageUtf16() {
 		GsonMessageConverter converter = new GsonMessageConverter();
 		MimeType contentType = new MimeType("application", "json", StandardCharsets.UTF_16BE);
 		Map<String, Object> map = new HashMap<>();
@@ -170,7 +170,7 @@ public class GsonMessageConverterTests {
 	}
 
 	@Test
-	public void toMessageUtf16String() {
+	void toMessageUtf16String() {
 		GsonMessageConverter converter = new GsonMessageConverter();
 		converter.setSerializedPayloadClass(String.class);
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/converter/JsonbMessageConverterTests.java b/spring-messaging/src/test/java/org/springframework/messaging/converter/JsonbMessageConverterTests.java
index 6b626a4247..2bd010190d 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/converter/JsonbMessageConverterTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/converter/JsonbMessageConverterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,16 +42,16 @@ import static org.assertj.core.api.Assertions.within;
  * @author Rossen Stoyanchev
  * @author Sebastien Deleuze
  */
-public class JsonbMessageConverterTests {
+class JsonbMessageConverterTests {
 
 	@Test
-	public void defaultConstructor() {
+	void defaultConstructor() {
 		JsonbMessageConverter converter = new JsonbMessageConverter();
 		assertThat(converter.getSupportedMimeTypes()).contains(new MimeType("application", "json"));
 	}
 
 	@Test
-	public void fromMessage() {
+	void fromMessage() {
 		JsonbMessageConverter converter = new JsonbMessageConverter();
 		String payload = "{\"array\":[\"Foo\",\"Bar\"]," +
 				"\"number\":42,\"string\":\"Foo\",\"bool\":true,\"fraction\":42.0}";
@@ -66,7 +66,7 @@ public class JsonbMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageUntyped() {
+	void fromMessageUntyped() {
 		JsonbMessageConverter converter = new JsonbMessageConverter();
 		String payload = "{\"array\":[\"Foo\",\"Bar\"]," +
 				"\"number\":42,\"string\":\"Foo\",\"bool\":true,\"fraction\":42.0}";
@@ -82,7 +82,7 @@ public class JsonbMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageMatchingInstance() {
+	void fromMessageMatchingInstance() {
 		MyBean myBean = new MyBean();
 		JsonbMessageConverter converter = new JsonbMessageConverter();
 		Message<?> message = MessageBuilder.withPayload(myBean).build();
@@ -90,7 +90,7 @@ public class JsonbMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageInvalidJson() {
+	void fromMessageInvalidJson() {
 		JsonbMessageConverter converter = new JsonbMessageConverter();
 		String payload = "FooBar";
 		Message<?> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
@@ -99,7 +99,7 @@ public class JsonbMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageValidJsonWithUnknownProperty() {
+	void fromMessageValidJsonWithUnknownProperty() {
 		JsonbMessageConverter converter = new JsonbMessageConverter();
 		String payload = "{\"string\":\"string\",\"unknownProperty\":\"value\"}";
 		Message<?> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
@@ -108,7 +108,7 @@ public class JsonbMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageToList() throws Exception {
+	void fromMessageToList() throws Exception {
 		JsonbMessageConverter converter = new JsonbMessageConverter();
 		String payload = "[1, 2, 3, 4, 5, 6, 7, 8, 9]";
 		Message<?> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
@@ -122,7 +122,7 @@ public class JsonbMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageToMessageWithPojo() throws Exception {
+	void fromMessageToMessageWithPojo() throws Exception {
 		JsonbMessageConverter converter = new JsonbMessageConverter();
 		String payload = "{\"string\":\"foo\"}";
 		Message<?> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
@@ -136,7 +136,7 @@ public class JsonbMessageConverterTests {
 	}
 
 	@Test
-	public void toMessage() {
+	void toMessage() {
 		JsonbMessageConverter converter = new JsonbMessageConverter();
 		MyBean payload = new MyBean();
 		payload.setString("Foo");
@@ -157,7 +157,7 @@ public class JsonbMessageConverterTests {
 	}
 
 	@Test
-	public void toMessageUtf16() {
+	void toMessageUtf16() {
 		JsonbMessageConverter converter = new JsonbMessageConverter();
 		MimeType contentType = new MimeType("application", "json", StandardCharsets.UTF_16BE);
 		Map<String, Object> map = new HashMap<>();
@@ -171,7 +171,7 @@ public class JsonbMessageConverterTests {
 	}
 
 	@Test
-	public void toMessageUtf16String() {
+	void toMessageUtf16String() {
 		JsonbMessageConverter converter = new JsonbMessageConverter();
 		converter.setSerializedPayloadClass(String.class);
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/converter/MappingJackson2MessageConverterTests.java b/spring-messaging/src/test/java/org/springframework/messaging/converter/MappingJackson2MessageConverterTests.java
index f94daa9207..0f3cc097dd 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/converter/MappingJackson2MessageConverterTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/converter/MappingJackson2MessageConverterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,10 +43,10 @@ import static org.assertj.core.api.Assertions.within;
  * @author Rossen Stoyanchev
  * @author Sebastien Deleuze
  */
-public class MappingJackson2MessageConverterTests {
+class MappingJackson2MessageConverterTests {
 
 	@Test
-	public void defaultConstructor() {
+	void defaultConstructor() {
 		MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
 		assertThat(converter.getSupportedMimeTypes()).contains(new MimeType("application", "json"));
 		assertThat(converter.getObjectMapper().getDeserializationConfig()
@@ -73,7 +73,7 @@ public class MappingJackson2MessageConverterTests {
 	}
 
 	@Test
-	public void fromMessage() {
+	void fromMessage() {
 		MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
 		String payload = "{\"bytes\":\"AQI=\",\"array\":[\"Foo\",\"Bar\"]," +
 				"\"number\":42,\"string\":\"Foo\",\"bool\":true,\"fraction\":42.0}";
@@ -89,7 +89,7 @@ public class MappingJackson2MessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageUntyped() {
+	void fromMessageUntyped() {
 		MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
 		String payload = "{\"bytes\":\"AQI=\",\"array\":[\"Foo\",\"Bar\"]," +
 				"\"number\":42,\"string\":\"Foo\",\"bool\":true,\"fraction\":42.0}";
@@ -114,7 +114,7 @@ public class MappingJackson2MessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageInvalidJson() {
+	void fromMessageInvalidJson() {
 		MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
 		String payload = "FooBar";
 		Message<?> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
@@ -123,7 +123,7 @@ public class MappingJackson2MessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageValidJsonWithUnknownProperty() {
+	void fromMessageValidJsonWithUnknownProperty() {
 		MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
 		String payload = "{\"string\":\"string\",\"unknownProperty\":\"value\"}";
 		Message<?> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
@@ -160,7 +160,7 @@ public class MappingJackson2MessageConverterTests {
 	}
 
 	@Test
-	public void toMessage() {
+	void toMessage() {
 		MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
 		MyBean payload = new MyBean();
 		payload.setString("Foo");
@@ -183,7 +183,7 @@ public class MappingJackson2MessageConverterTests {
 	}
 
 	@Test
-	public void toMessageUtf16() {
+	void toMessageUtf16() {
 		MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
 		MimeType contentType = new MimeType("application", "json", StandardCharsets.UTF_16BE);
 		Map<String, Object> map = new HashMap<>();
@@ -197,7 +197,7 @@ public class MappingJackson2MessageConverterTests {
 	}
 
 	@Test
-	public void toMessageUtf16String() {
+	void toMessageUtf16String() {
 		MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
 		converter.setSerializedPayloadClass(String.class);
 
@@ -213,7 +213,7 @@ public class MappingJackson2MessageConverterTests {
 	}
 
 	@Test
-	public void toMessageJsonView() throws Exception {
+	void toMessageJsonView() throws Exception {
 		MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
 
 		Map<String, Object> map = new HashMap<>();
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/converter/MarshallingMessageConverterTests.java b/spring-messaging/src/test/java/org/springframework/messaging/converter/MarshallingMessageConverterTests.java
index 19aad50fdd..921d4a5f45 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/converter/MarshallingMessageConverterTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/converter/MarshallingMessageConverterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,6 @@
 
 package org.springframework.messaging.converter;
 
-import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 
 import jakarta.xml.bind.annotation.XmlRootElement;
@@ -39,13 +38,13 @@ import static org.xmlunit.diff.DifferenceEvaluators.downgradeDifferencesToEqual;
 /**
  * @author Arjen Poutsma
  */
-public class MarshallingMessageConverterTests {
+class MarshallingMessageConverterTests {
 
 	private MarshallingMessageConverter converter;
 
 
 	@BeforeEach
-	public void createMarshaller() throws Exception {
+	void createMarshaller() throws Exception {
 		Jaxb2Marshaller marshaller = new Jaxb2Marshaller();
 		marshaller.setClassesToBeBound(MyBean.class);
 		marshaller.afterPropertiesSet();
@@ -55,7 +54,7 @@ public class MarshallingMessageConverterTests {
 
 
 	@Test
-	public void fromMessage() throws Exception {
+	void fromMessage() {
 		String payload = "<myBean><name>Foo</name></myBean>";
 		Message<?> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
 		MyBean actual = (MyBean) this.converter.fromMessage(message, MyBean.class);
@@ -65,7 +64,7 @@ public class MarshallingMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageInvalidXml() throws Exception {
+	void fromMessageInvalidXml() {
 		String payload = "<myBean><name>Foo</name><myBean>";
 		Message<?> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
 		assertThatExceptionOfType(MessageConversionException.class).isThrownBy(() ->
@@ -73,7 +72,7 @@ public class MarshallingMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageValidXmlWithUnknownProperty() throws IOException {
+	void fromMessageValidXmlWithUnknownProperty() {
 		String payload = "<myBean><age>42</age><myBean>";
 		Message<?> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
 		assertThatExceptionOfType(MessageConversionException.class).isThrownBy(() ->
@@ -81,7 +80,7 @@ public class MarshallingMessageConverterTests {
 	}
 
 	@Test
-	public void toMessage() throws Exception {
+	void toMessage() {
 		MyBean payload = new MyBean();
 		payload.setName("Foo");
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/converter/MessageConverterTests.java b/spring-messaging/src/test/java/org/springframework/messaging/converter/MessageConverterTests.java
index d7b4d7b931..d8b2569dac 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/converter/MessageConverterTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/converter/MessageConverterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,13 +39,13 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  *
  * @author Rossen Stoyanchev
  */
-public class MessageConverterTests {
+class MessageConverterTests {
 
 	private TestMessageConverter converter = new TestMessageConverter();
 
 
 	@Test
-	public void supportsTargetClass() {
+	void supportsTargetClass() {
 		Message<String> message = MessageBuilder.withPayload("ABC").build();
 
 		assertThat(this.converter.fromMessage(message, String.class)).isEqualTo("success-from");
@@ -53,7 +53,7 @@ public class MessageConverterTests {
 	}
 
 	@Test
-	public void supportsMimeType() {
+	void supportsMimeType() {
 		Message<String> message = MessageBuilder.withPayload(
 				"ABC").setHeader(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.TEXT_PLAIN).build();
 
@@ -61,7 +61,7 @@ public class MessageConverterTests {
 	}
 
 	@Test
-	public void supportsMimeTypeNotSupported() {
+	void supportsMimeTypeNotSupported() {
 		Message<String> message = MessageBuilder.withPayload(
 				"ABC").setHeader(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.APPLICATION_JSON).build();
 
@@ -69,13 +69,13 @@ public class MessageConverterTests {
 	}
 
 	@Test
-	public void supportsMimeTypeNotSpecified() {
+	void supportsMimeTypeNotSpecified() {
 		Message<String> message = MessageBuilder.withPayload("ABC").build();
 		assertThat(this.converter.fromMessage(message, String.class)).isEqualTo("success-from");
 	}
 
 	@Test
-	public void supportsMimeTypeNoneConfigured() {
+	void supportsMimeTypeNoneConfigured() {
 		Message<String> message = MessageBuilder.withPayload(
 				"ABC").setHeader(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.APPLICATION_JSON).build();
 		this.converter = new TestMessageConverter(new MimeType[0]);
@@ -84,7 +84,7 @@ public class MessageConverterTests {
 	}
 
 	@Test
-	public void canConvertFromStrictContentTypeMatch() {
+	void canConvertFromStrictContentTypeMatch() {
 		this.converter = new TestMessageConverter(MimeTypeUtils.TEXT_PLAIN);
 		this.converter.setStrictContentTypeMatch(true);
 
@@ -98,13 +98,13 @@ public class MessageConverterTests {
 	}
 
 	@Test
-	public void setStrictContentTypeMatchWithNoSupportedMimeTypes() {
+	void setStrictContentTypeMatchWithNoSupportedMimeTypes() {
 		this.converter = new TestMessageConverter(new MimeType[0]);
 		assertThatIllegalArgumentException().isThrownBy(() -> this.converter.setStrictContentTypeMatch(true));
 	}
 
 	@Test
-	public void toMessageWithHeaders() {
+	void toMessageWithHeaders() {
 		Map<String, Object> map = new HashMap<>();
 		map.put("foo", "bar");
 		MessageHeaders headers = new MessageHeaders(map);
@@ -117,7 +117,7 @@ public class MessageConverterTests {
 	}
 
 	@Test
-	public void toMessageWithMutableMessageHeaders() {
+	void toMessageWithMutableMessageHeaders() {
 		SimpMessageHeaderAccessor accessor = SimpMessageHeaderAccessor.create(SimpMessageType.MESSAGE);
 		accessor.setHeader("foo", "bar");
 		accessor.setNativeHeader("fooNative", "barNative");
@@ -133,7 +133,7 @@ public class MessageConverterTests {
 	}
 
 	@Test
-	public void toMessageContentTypeHeader() {
+	void toMessageContentTypeHeader() {
 		Message<?> message = this.converter.toMessage("ABC", null);
 		assertThat(message.getHeaders().get(MessageHeaders.CONTENT_TYPE)).isEqualTo(MimeTypeUtils.TEXT_PLAIN);
 	}
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/converter/SimpleMessageConverterTests.java b/spring-messaging/src/test/java/org/springframework/messaging/converter/SimpleMessageConverterTests.java
index 80fd5456d6..ede19507d1 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/converter/SimpleMessageConverterTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/converter/SimpleMessageConverterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -32,14 +32,14 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Rossen Stoyanchev
  */
-public class SimpleMessageConverterTests {
+class SimpleMessageConverterTests {
 
 	private final SimpleMessageConverter converter = new SimpleMessageConverter();
 
 
 	@Test
-	public void toMessageWithPayloadAndHeaders() {
-		MessageHeaders headers = new MessageHeaders(Collections.<String, Object>singletonMap("foo", "bar"));
+	void toMessageWithPayloadAndHeaders() {
+		MessageHeaders headers = new MessageHeaders(Collections.singletonMap("foo", "bar"));
 		Message<?> message = this.converter.toMessage("payload", headers);
 
 		assertThat(message.getPayload()).isEqualTo("payload");
@@ -47,7 +47,7 @@ public class SimpleMessageConverterTests {
 	}
 
 	@Test
-	public void toMessageWithPayloadAndMutableHeaders() {
+	void toMessageWithPayloadAndMutableHeaders() {
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 		accessor.setHeader("foo", "bar");
 		accessor.setLeaveMutable(true);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/converter/StringMessageConverterTests.java b/spring-messaging/src/test/java/org/springframework/messaging/converter/StringMessageConverterTests.java
index f6be00b971..9deb533bd2 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/converter/StringMessageConverterTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/converter/StringMessageConverterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,33 +35,33 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Rossen Stoyanchev
  */
-public class StringMessageConverterTests {
+class StringMessageConverterTests {
 
 	private final StringMessageConverter converter = new StringMessageConverter();
 
 
 	@Test
-	public void fromByteArrayMessage() {
+	void fromByteArrayMessage() {
 		Message<byte[]> message = MessageBuilder.withPayload(
 				"ABC".getBytes()).setHeader(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.TEXT_PLAIN).build();
 		assertThat(this.converter.fromMessage(message, String.class)).isEqualTo("ABC");
 	}
 
 	@Test
-	public void fromStringMessage() {
+	void fromStringMessage() {
 		Message<String> message = MessageBuilder.withPayload(
 				"ABC").setHeader(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.TEXT_PLAIN).build();
 		assertThat(this.converter.fromMessage(message, String.class)).isEqualTo("ABC");
 	}
 
 	@Test
-	public void fromMessageNoContentTypeHeader() {
+	void fromMessageNoContentTypeHeader() {
 		Message<byte[]> message = MessageBuilder.withPayload("ABC".getBytes()).build();
 		assertThat(this.converter.fromMessage(message, String.class)).isEqualTo("ABC");
 	}
 
 	@Test
-	public void fromMessageCharset() {
+	void fromMessageCharset() {
 		String payload = "H\u00e9llo W\u00f6rld";
 		Message<byte[]> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.ISO_8859_1))
 				.setHeader(MessageHeaders.CONTENT_TYPE, new MimeType("text", "plain", StandardCharsets.ISO_8859_1)).build();
@@ -69,27 +69,27 @@ public class StringMessageConverterTests {
 	}
 
 	@Test
-	public void fromMessageDefaultCharset() {
+	void fromMessageDefaultCharset() {
 		String payload = "H\u00e9llo W\u00f6rld";
 		Message<byte[]> message = MessageBuilder.withPayload(payload.getBytes(StandardCharsets.UTF_8)).build();
 		assertThat(this.converter.fromMessage(message, String.class)).isEqualTo(payload);
 	}
 
 	@Test
-	public void fromMessageTargetClassNotSupported() {
+	void fromMessageTargetClassNotSupported() {
 		Message<byte[]> message = MessageBuilder.withPayload("ABC".getBytes()).build();
 		assertThat(this.converter.fromMessage(message, Integer.class)).isNull();
 	}
 
 	@Test
-	public void fromMessageByteArray() {
+	void fromMessageByteArray() {
 		Message<byte[]> message = MessageBuilder.withPayload(
 				"ABC".getBytes()).setHeader(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.TEXT_PLAIN).build();
 		assertThat(this.converter.fromMessage(message, String.class)).isEqualTo("ABC");
 	}
 
 	@Test
-	public void toMessage() {
+	void toMessage() {
 		Map<String, Object> map = new HashMap<>();
 		map.put(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.TEXT_PLAIN);
 		MessageHeaders headers = new MessageHeaders(map);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/core/CachingDestinationResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/core/CachingDestinationResolverTests.java
index 62c02cfdb7..911b2d9bc2 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/core/CachingDestinationResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/core/CachingDestinationResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,11 +31,10 @@ import static org.mockito.Mockito.verify;
  * @author Agim Emruli
  * @author Juergen Hoeller
  */
-public class CachingDestinationResolverTests {
+class CachingDestinationResolverTests {
 
 	@Test
-	public void cachedDestination() {
-		@SuppressWarnings("unchecked")
+	void cachedDestination() {
 		DestinationResolver<String> resolver = mock();
 		CachingDestinationResolverProxy<String> resolverProxy = new CachingDestinationResolverProxy<>(resolver);
 
@@ -52,14 +51,14 @@ public class CachingDestinationResolverTests {
 	}
 
 	@Test
-	public void noTargetSet() {
+	void noTargetSet() {
 		CachingDestinationResolverProxy<String> resolverProxy = new CachingDestinationResolverProxy<>();
 		assertThatIllegalArgumentException().isThrownBy(
 				resolverProxy::afterPropertiesSet);
 	}
 
 	@Test
-	public void nullTargetThroughConstructor() {
+	void nullTargetThroughConstructor() {
 		assertThatIllegalArgumentException().isThrownBy(() ->
 				new CachingDestinationResolverProxy<String>(null));
 	}
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/core/DestinationResolvingMessagingTemplateTests.java b/spring-messaging/src/test/java/org/springframework/messaging/core/DestinationResolvingMessagingTemplateTests.java
index 1fb3dc9820..28340a11c9 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/core/DestinationResolvingMessagingTemplateTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/core/DestinationResolvingMessagingTemplateTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,7 +36,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  *
  * @author Rossen Stoyanchev
  */
-public class DestinationResolvingMessagingTemplateTests {
+class DestinationResolvingMessagingTemplateTests {
 
 	private TestDestinationResolvingMessagingTemplate template;
 
@@ -48,7 +48,7 @@ public class DestinationResolvingMessagingTemplateTests {
 
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 
 		TestMessageChannelDestinationResolver resolver = new TestMessageChannelDestinationResolver();
 
@@ -58,14 +58,14 @@ public class DestinationResolvingMessagingTemplateTests {
 		this.template = new TestDestinationResolvingMessagingTemplate();
 		this.template.setDestinationResolver(resolver);
 
-		this.headers = Collections.<String, Object>singletonMap("key", "value");
+		this.headers = Collections.singletonMap("key", "value");
 
 		this.postProcessor = new TestMessagePostProcessor();
 	}
 
 
 	@Test
-	public void send() {
+	void send() {
 		Message<?> message = new GenericMessage<Object>("payload");
 		this.template.send("myChannel", message);
 
@@ -74,14 +74,14 @@ public class DestinationResolvingMessagingTemplateTests {
 	}
 
 	@Test
-	public void sendNoDestinationResolver() {
+	void sendNoDestinationResolver() {
 		TestDestinationResolvingMessagingTemplate template = new TestDestinationResolvingMessagingTemplate();
 		assertThatIllegalStateException().isThrownBy(() ->
 				template.send("myChannel", new GenericMessage<Object>("payload")));
 	}
 
 	@Test
-	public void convertAndSendPayload() {
+	void convertAndSendPayload() {
 		this.template.convertAndSend("myChannel", "payload");
 
 		assertThat(this.template.messageChannel).isSameAs(this.myChannel);
@@ -90,7 +90,7 @@ public class DestinationResolvingMessagingTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendPayloadAndHeaders() {
+	void convertAndSendPayloadAndHeaders() {
 		this.template.convertAndSend("myChannel", "payload", this.headers);
 
 		assertThat(this.template.messageChannel).isSameAs(this.myChannel);
@@ -100,7 +100,7 @@ public class DestinationResolvingMessagingTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendPayloadWithPostProcessor() {
+	void convertAndSendPayloadWithPostProcessor() {
 		this.template.convertAndSend("myChannel", "payload", this.postProcessor);
 
 		assertThat(this.template.messageChannel).isSameAs(this.myChannel);
@@ -112,7 +112,7 @@ public class DestinationResolvingMessagingTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendPayloadAndHeadersWithPostProcessor() {
+	void convertAndSendPayloadAndHeadersWithPostProcessor() {
 		this.template.convertAndSend("myChannel", "payload", this.headers, this.postProcessor);
 
 		assertThat(this.template.messageChannel).isSameAs(this.myChannel);
@@ -125,7 +125,7 @@ public class DestinationResolvingMessagingTemplateTests {
 	}
 
 	@Test
-	public void receive() {
+	void receive() {
 		Message<?> expected = new GenericMessage<Object>("payload");
 		this.template.setReceiveMessage(expected);
 		Message<?> actual = this.template.receive("myChannel");
@@ -135,7 +135,7 @@ public class DestinationResolvingMessagingTemplateTests {
 	}
 
 	@Test
-	public void receiveAndConvert() {
+	void receiveAndConvert() {
 		Message<?> expected = new GenericMessage<Object>("payload");
 		this.template.setReceiveMessage(expected);
 		String payload = this.template.receiveAndConvert("myChannel", String.class);
@@ -145,7 +145,7 @@ public class DestinationResolvingMessagingTemplateTests {
 	}
 
 	@Test
-	public void sendAndReceive() {
+	void sendAndReceive() {
 		Message<?> requestMessage = new GenericMessage<Object>("request");
 		Message<?> responseMessage = new GenericMessage<Object>("response");
 		this.template.setReceiveMessage(responseMessage);
@@ -157,7 +157,7 @@ public class DestinationResolvingMessagingTemplateTests {
 	}
 
 	@Test
-	public void convertSendAndReceive() {
+	void convertSendAndReceive() {
 		Message<?> responseMessage = new GenericMessage<Object>("response");
 		this.template.setReceiveMessage(responseMessage);
 		String actual = this.template.convertSendAndReceive("myChannel", "request", String.class);
@@ -168,7 +168,7 @@ public class DestinationResolvingMessagingTemplateTests {
 	}
 
 	@Test
-	public void convertSendAndReceiveWithHeaders() {
+	void convertSendAndReceiveWithHeaders() {
 		Message<?> responseMessage = new GenericMessage<Object>("response");
 		this.template.setReceiveMessage(responseMessage);
 		String actual = this.template.convertSendAndReceive("myChannel", "request", this.headers, String.class);
@@ -180,7 +180,7 @@ public class DestinationResolvingMessagingTemplateTests {
 	}
 
 	@Test
-	public void convertSendAndReceiveWithPostProcessor() {
+	void convertSendAndReceiveWithPostProcessor() {
 		Message<?> responseMessage = new GenericMessage<Object>("response");
 		this.template.setReceiveMessage(responseMessage);
 		String actual = this.template.convertSendAndReceive("myChannel", "request", String.class, this.postProcessor);
@@ -192,7 +192,7 @@ public class DestinationResolvingMessagingTemplateTests {
 	}
 
 	@Test
-	public void convertSendAndReceiveWithHeadersAndPostProcessor() {
+	void convertSendAndReceiveWithHeadersAndPostProcessor() {
 		Message<?> responseMessage = new GenericMessage<Object>("response");
 		this.template.setReceiveMessage(responseMessage);
 		String actual = this.template.convertSendAndReceive("myChannel", "request", this.headers,
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/core/GenericMessagingTemplateTests.java b/spring-messaging/src/test/java/org/springframework/messaging/core/GenericMessagingTemplateTests.java
index 472ea141bc..51128e47ca 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/core/GenericMessagingTemplateTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/core/GenericMessagingTemplateTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -51,7 +51,7 @@ import static org.mockito.Mockito.verify;
  * @author Rossen Stoyanchev
  * @author Gary Russell
  */
-public class GenericMessagingTemplateTests {
+class GenericMessagingTemplateTests {
 
 	private GenericMessagingTemplate template;
 
@@ -61,7 +61,7 @@ public class GenericMessagingTemplateTests {
 
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 		this.messageChannel = new StubMessageChannel();
 		this.template = new GenericMessagingTemplate();
 		this.template.setDefaultDestination(this.messageChannel);
@@ -71,7 +71,7 @@ public class GenericMessagingTemplateTests {
 	}
 
 	@Test
-	public void sendWithTimeout() {
+	void sendWithTimeout() {
 		SubscribableChannel channel = mock();
 		final AtomicReference<Message<?>> sent = new AtomicReference<>();
 		willAnswer(invocation -> {
@@ -90,7 +90,7 @@ public class GenericMessagingTemplateTests {
 	}
 
 	@Test
-	public void sendWithTimeoutMutable() {
+	void sendWithTimeoutMutable() {
 		SubscribableChannel channel = mock();
 		final AtomicReference<Message<?>> sent = new AtomicReference<>();
 		willAnswer(invocation -> {
@@ -109,7 +109,7 @@ public class GenericMessagingTemplateTests {
 	}
 
 	@Test
-	public void sendAndReceive() {
+	void sendAndReceive() {
 		SubscribableChannel channel = new ExecutorSubscribableChannel(this.executor);
 		channel.subscribe(message -> {
 			MessageChannel replyChannel = (MessageChannel) message.getHeaders().getReplyChannel();
@@ -121,7 +121,7 @@ public class GenericMessagingTemplateTests {
 	}
 
 	@Test
-	public void sendAndReceiveTimeout() throws InterruptedException {
+	void sendAndReceiveTimeout() throws InterruptedException {
 		final AtomicReference<Throwable> failure = new AtomicReference<>();
 		final CountDownLatch latch = new CountDownLatch(1);
 
@@ -147,7 +147,7 @@ public class GenericMessagingTemplateTests {
 	}
 
 	@Test
-	public void sendAndReceiveVariableTimeout() throws InterruptedException {
+	void sendAndReceiveVariableTimeout() throws InterruptedException {
 		final AtomicReference<Throwable> failure = new AtomicReference<>();
 		final CountDownLatch latch = new CountDownLatch(1);
 
@@ -177,7 +177,7 @@ public class GenericMessagingTemplateTests {
 	}
 
 	@Test
-	public void sendAndReceiveVariableTimeoutCustomHeaders() throws InterruptedException {
+	void sendAndReceiveVariableTimeoutCustomHeaders() throws InterruptedException {
 		final AtomicReference<Throwable> failure = new AtomicReference<>();
 		final CountDownLatch latch = new CountDownLatch(1);
 
@@ -209,7 +209,7 @@ public class GenericMessagingTemplateTests {
 	}
 
 	private MessageHandler createLateReplier(final CountDownLatch latch, final AtomicReference<Throwable> failure) {
-		MessageHandler handler = message -> {
+		return message -> {
 			try {
 				Thread.sleep(500);
 				MessageChannel replyChannel = (MessageChannel) message.getHeaders().getReplyChannel();
@@ -231,11 +231,10 @@ public class GenericMessagingTemplateTests {
 				latch.countDown();
 			}
 		};
-		return handler;
 	}
 
 	@Test
-	public void convertAndSendWithSimpMessageHeaders() {
+	void convertAndSendWithSimpMessageHeaders() {
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 		accessor.setHeader("key", "value");
 		accessor.setLeaveMutable(true);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/core/MessageReceivingTemplateTests.java b/spring-messaging/src/test/java/org/springframework/messaging/core/MessageReceivingTemplateTests.java
index 2c607930fe..491171a0a9 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/core/MessageReceivingTemplateTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/core/MessageReceivingTemplateTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,18 +37,18 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  * @author Rossen Stoyanchev
  * @see MessageRequestReplyTemplateTests
  */
-public class MessageReceivingTemplateTests {
+class MessageReceivingTemplateTests {
 
 	private TestMessagingTemplate template;
 
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 		this.template = new TestMessagingTemplate();
 	}
 
 	@Test
-	public void receive() {
+	void receive() {
 		Message<?> expected = new GenericMessage<>("payload");
 		this.template.setDefaultDestination("home");
 		this.template.setReceiveMessage(expected);
@@ -59,13 +59,13 @@ public class MessageReceivingTemplateTests {
 	}
 
 	@Test
-	public void receiveMissingDefaultDestination() {
+	void receiveMissingDefaultDestination() {
 		assertThatIllegalStateException().isThrownBy(
 				this.template::receive);
 	}
 
 	@Test
-	public void receiveFromDestination() {
+	void receiveFromDestination() {
 		Message<?> expected = new GenericMessage<>("payload");
 		this.template.setReceiveMessage(expected);
 		Message<?> actual = this.template.receive("somewhere");
@@ -75,7 +75,7 @@ public class MessageReceivingTemplateTests {
 	}
 
 	@Test
-	public void receiveAndConvert() {
+	void receiveAndConvert() {
 		Message<?> expected = new GenericMessage<>("payload");
 		this.template.setDefaultDestination("home");
 		this.template.setReceiveMessage(expected);
@@ -86,7 +86,7 @@ public class MessageReceivingTemplateTests {
 	}
 
 	@Test
-	public void receiveAndConvertFromDestination() {
+	void receiveAndConvertFromDestination() {
 		Message<?> expected = new GenericMessage<>("payload");
 		this.template.setReceiveMessage(expected);
 		String payload = this.template.receiveAndConvert("somewhere", String.class);
@@ -96,7 +96,7 @@ public class MessageReceivingTemplateTests {
 	}
 
 	@Test
-	public void receiveAndConvertFailed() {
+	void receiveAndConvertFailed() {
 		Message<?> expected = new GenericMessage<>("not a number test");
 		this.template.setReceiveMessage(expected);
 		this.template.setMessageConverter(new GenericMessageConverter());
@@ -107,7 +107,7 @@ public class MessageReceivingTemplateTests {
 	}
 
 	@Test
-	public void receiveAndConvertNoConverter() {
+	void receiveAndConvertNoConverter() {
 		Message<?> expected = new GenericMessage<>("payload");
 		this.template.setDefaultDestination("home");
 		this.template.setReceiveMessage(expected);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/core/MessageRequestReplyTemplateTests.java b/spring-messaging/src/test/java/org/springframework/messaging/core/MessageRequestReplyTemplateTests.java
index e4e70aeb92..426de797c8 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/core/MessageRequestReplyTemplateTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/core/MessageRequestReplyTemplateTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,7 +35,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  *
  * @see MessageReceivingTemplateTests
  */
-public class MessageRequestReplyTemplateTests {
+class MessageRequestReplyTemplateTests {
 
 	private TestMessagingTemplate template;
 
@@ -45,15 +45,15 @@ public class MessageRequestReplyTemplateTests {
 
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 		this.template = new TestMessagingTemplate();
 		this.postProcessor = new TestMessagePostProcessor();
-		this.headers = Collections.<String, Object>singletonMap("key", "value");
+		this.headers = Collections.singletonMap("key", "value");
 	}
 
 
 	@Test
-	public void sendAndReceive() {
+	void sendAndReceive() {
 		Message<?> requestMessage = new GenericMessage<Object>("request");
 		Message<?> responseMessage = new GenericMessage<Object>("response");
 		this.template.setDefaultDestination("home");
@@ -66,13 +66,13 @@ public class MessageRequestReplyTemplateTests {
 	}
 
 	@Test
-	public void sendAndReceiveMissingDestination() {
+	void sendAndReceiveMissingDestination() {
 		assertThatIllegalStateException().isThrownBy(() ->
 				this.template.sendAndReceive(new GenericMessage<Object>("request")));
 	}
 
 	@Test
-	public void sendAndReceiveToDestination() {
+	void sendAndReceiveToDestination() {
 		Message<?> requestMessage = new GenericMessage<Object>("request");
 		Message<?> responseMessage = new GenericMessage<Object>("response");
 		this.template.setReceiveMessage(responseMessage);
@@ -84,7 +84,7 @@ public class MessageRequestReplyTemplateTests {
 	}
 
 	@Test
-	public void convertAndSend() {
+	void convertAndSend() {
 		Message<?> responseMessage = new GenericMessage<Object>("response");
 		this.template.setDefaultDestination("home");
 		this.template.setReceiveMessage(responseMessage);
@@ -96,7 +96,7 @@ public class MessageRequestReplyTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendToDestination() {
+	void convertAndSendToDestination() {
 		Message<?> responseMessage = new GenericMessage<Object>("response");
 		this.template.setReceiveMessage(responseMessage);
 		String response = this.template.convertSendAndReceive("somewhere", "request", String.class);
@@ -107,7 +107,7 @@ public class MessageRequestReplyTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendToDestinationWithHeaders() {
+	void convertAndSendToDestinationWithHeaders() {
 		Message<?> responseMessage = new GenericMessage<Object>("response");
 		this.template.setReceiveMessage(responseMessage);
 		String response = this.template.convertSendAndReceive("somewhere", "request", this.headers, String.class);
@@ -119,7 +119,7 @@ public class MessageRequestReplyTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendWithPostProcessor() {
+	void convertAndSendWithPostProcessor() {
 		Message<?> responseMessage = new GenericMessage<Object>("response");
 		this.template.setDefaultDestination("home");
 		this.template.setReceiveMessage(responseMessage);
@@ -132,7 +132,7 @@ public class MessageRequestReplyTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendToDestinationWithPostProcessor() {
+	void convertAndSendToDestinationWithPostProcessor() {
 		Message<?> responseMessage = new GenericMessage<Object>("response");
 		this.template.setReceiveMessage(responseMessage);
 		String response = this.template.convertSendAndReceive("somewhere", "request", String.class, this.postProcessor);
@@ -144,7 +144,7 @@ public class MessageRequestReplyTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendToDestinationWithHeadersAndPostProcessor() {
+	void convertAndSendToDestinationWithHeadersAndPostProcessor() {
 		Message<?> responseMessage = new GenericMessage<Object>("response");
 		this.template.setReceiveMessage(responseMessage);
 		String response = this.template.convertSendAndReceive("somewhere", "request", this.headers,
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/core/MessageSendingTemplateTests.java b/spring-messaging/src/test/java/org/springframework/messaging/core/MessageSendingTemplateTests.java
index 8ce5766ae7..7d7bf635a8 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/core/MessageSendingTemplateTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/core/MessageSendingTemplateTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,8 +17,8 @@
 package org.springframework.messaging.core;
 
 import java.nio.charset.StandardCharsets;
-import java.util.Arrays;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import org.junit.jupiter.api.BeforeEach;
@@ -45,7 +45,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  *
  * @author Rossen Stoyanchev
  */
-public class MessageSendingTemplateTests {
+class MessageSendingTemplateTests {
 
 	private TestMessageSendingTemplate template;
 
@@ -55,7 +55,7 @@ public class MessageSendingTemplateTests {
 
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 		this.template = new TestMessageSendingTemplate();
 		this.postProcessor = new TestMessagePostProcessor();
 		this.headers = new HashMap<>();
@@ -63,7 +63,7 @@ public class MessageSendingTemplateTests {
 	}
 
 	@Test
-	public void send() {
+	void send() {
 		Message<?> message = new GenericMessage<Object>("payload");
 		this.template.setDefaultDestination("home");
 		this.template.send(message);
@@ -73,7 +73,7 @@ public class MessageSendingTemplateTests {
 	}
 
 	@Test
-	public void sendToDestination() {
+	void sendToDestination() {
 		Message<?> message = new GenericMessage<Object>("payload");
 		this.template.send("somewhere", message);
 
@@ -82,14 +82,14 @@ public class MessageSendingTemplateTests {
 	}
 
 	@Test
-	public void sendMissingDestination() {
+	void sendMissingDestination() {
 		Message<?> message = new GenericMessage<Object>("payload");
 		assertThatIllegalStateException().isThrownBy(() ->
 				this.template.send(message));
 	}
 
 	@Test
-	public void convertAndSend() {
+	void convertAndSend() {
 		this.template.convertAndSend("somewhere", "payload", headers, this.postProcessor);
 
 		assertThat(this.template.destination).isEqualTo("somewhere");
@@ -102,7 +102,7 @@ public class MessageSendingTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendPayload() {
+	void convertAndSendPayload() {
 		this.template.setDefaultDestination("home");
 		this.template.convertAndSend("payload");
 
@@ -113,7 +113,7 @@ public class MessageSendingTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendPayloadToDestination() {
+	void convertAndSendPayloadToDestination() {
 		this.template.convertAndSend("somewhere", "payload");
 
 		assertThat(this.template.destination).isEqualTo("somewhere");
@@ -123,7 +123,7 @@ public class MessageSendingTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendPayloadAndHeadersToDestination() {
+	void convertAndSendPayloadAndHeadersToDestination() {
 		this.template.convertAndSend("somewhere", "payload", headers);
 
 		assertThat(this.template.destination).isEqualTo("somewhere");
@@ -133,7 +133,7 @@ public class MessageSendingTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendPayloadAndMutableHeadersToDestination() {
+	void convertAndSendPayloadAndMutableHeadersToDestination() {
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 		accessor.setHeader("foo", "bar");
 		accessor.setLeaveMutable(true);
@@ -149,7 +149,7 @@ public class MessageSendingTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendPayloadWithPostProcessor() {
+	void convertAndSendPayloadWithPostProcessor() {
 		this.template.setDefaultDestination("home");
 		this.template.convertAndSend((Object) "payload", this.postProcessor);
 
@@ -163,7 +163,7 @@ public class MessageSendingTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendPayloadWithPostProcessorToDestination() {
+	void convertAndSendPayloadWithPostProcessorToDestination() {
 		this.template.convertAndSend("somewhere", "payload", this.postProcessor);
 
 		assertThat(this.template.destination).isEqualTo("somewhere");
@@ -176,10 +176,10 @@ public class MessageSendingTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendNoMatchingConverter() {
+	void convertAndSendNoMatchingConverter() {
 
 		MessageConverter converter = new CompositeMessageConverter(
-				Arrays.<MessageConverter>asList(new MappingJackson2MessageConverter()));
+				List.of(new MappingJackson2MessageConverter()));
 		this.template.setMessageConverter(converter);
 
 		this.headers.put(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.APPLICATION_XML);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/DestinationPatternsMessageConditionTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/DestinationPatternsMessageConditionTests.java
index 0e61c3d9e0..1ed9b0b6b8 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/DestinationPatternsMessageConditionTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/DestinationPatternsMessageConditionTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,32 +29,34 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Rossen Stoyanchev
  */
-public class DestinationPatternsMessageConditionTests {
+class DestinationPatternsMessageConditionTests {
 
 	@Test
-	public void prependSlash() {
+	void prependSlash() {
 		DestinationPatternsMessageCondition c = condition("foo");
-		assertThat(c.getPatterns()).element(0).isEqualTo("/foo");
+		assertThat(c.getPatterns()).containsExactly("/foo");
 	}
 
 	@Test
-	public void prependSlashWithCustomPathSeparator() {
+	void prependSlashWithCustomPathSeparator() {
 		DestinationPatternsMessageCondition c =
 				new DestinationPatternsMessageCondition(new String[] {"foo"}, new AntPathMatcher("."));
 
-		assertThat(c.getPatterns()).element(0).as("Pre-pending should be disabled when not using '/' as path separator").isEqualTo("foo");
+		assertThat(c.getPatterns())
+				.as("Pre-pending should be disabled when not using '/' as path separator")
+				.containsExactly("foo");
 	}
 
 	// SPR-8255
 
 	@Test
-	public void prependNonEmptyPatternsOnly() {
+	void prependNonEmptyPatternsOnly() {
 		DestinationPatternsMessageCondition c = condition("");
 		assertThat(c.getPatterns()).element(0).asString().isEmpty();
 	}
 
 	@Test
-	public void combineEmptySets() {
+	void combineEmptySets() {
 		DestinationPatternsMessageCondition c1 = condition();
 		DestinationPatternsMessageCondition c2 = condition();
 
@@ -62,7 +64,7 @@ public class DestinationPatternsMessageConditionTests {
 	}
 
 	@Test
-	public void combineOnePatternWithEmptySet() {
+	void combineOnePatternWithEmptySet() {
 		DestinationPatternsMessageCondition c1 = condition("/type1", "/type2");
 		DestinationPatternsMessageCondition c2 = condition();
 
@@ -75,7 +77,7 @@ public class DestinationPatternsMessageConditionTests {
 	}
 
 	@Test
-	public void combineMultiplePatterns() {
+	void combineMultiplePatterns() {
 		DestinationPatternsMessageCondition c1 = condition("/t1", "/t2");
 		DestinationPatternsMessageCondition c2 = condition("/m1", "/m2");
 
@@ -84,7 +86,7 @@ public class DestinationPatternsMessageConditionTests {
 	}
 
 	@Test
-	public void matchDirectPath() {
+	void matchDirectPath() {
 		DestinationPatternsMessageCondition condition = condition("/foo");
 		DestinationPatternsMessageCondition match = condition.getMatchingCondition(messageTo("/foo"));
 
@@ -92,7 +94,7 @@ public class DestinationPatternsMessageConditionTests {
 	}
 
 	@Test
-	public void matchPattern() {
+	void matchPattern() {
 		DestinationPatternsMessageCondition condition = condition("/foo/*");
 		DestinationPatternsMessageCondition match = condition.getMatchingCondition(messageTo("/foo/bar"));
 
@@ -100,7 +102,7 @@ public class DestinationPatternsMessageConditionTests {
 	}
 
 	@Test
-	public void matchSortPatterns() {
+	void matchSortPatterns() {
 		DestinationPatternsMessageCondition condition = condition("/**", "/foo/bar", "/foo/*");
 		DestinationPatternsMessageCondition match = condition.getMatchingCondition(messageTo("/foo/bar"));
 		DestinationPatternsMessageCondition expected = condition("/foo/bar", "/foo/*", "/**");
@@ -109,7 +111,7 @@ public class DestinationPatternsMessageConditionTests {
 	}
 
 	@Test
-	public void compareEqualPatterns() {
+	void compareEqualPatterns() {
 		DestinationPatternsMessageCondition c1 = condition("/foo*");
 		DestinationPatternsMessageCondition c2 = condition("/foo*");
 
@@ -117,7 +119,7 @@ public class DestinationPatternsMessageConditionTests {
 	}
 
 	@Test
-	public void comparePatternSpecificity() {
+	void comparePatternSpecificity() {
 		DestinationPatternsMessageCondition c1 = condition("/fo*");
 		DestinationPatternsMessageCondition c2 = condition("/foo");
 
@@ -125,7 +127,7 @@ public class DestinationPatternsMessageConditionTests {
 	}
 
 	@Test
-	public void compareNumberOfMatchingPatterns() throws Exception {
+	void compareNumberOfMatchingPatterns() {
 		Message<?> message = messageTo("/foo");
 
 		DestinationPatternsMessageCondition c1 = condition("/foo", "bar");
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/MessageMappingReflectiveProcessorTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/MessageMappingReflectiveProcessorTests.java
index f33acab83a..32a3299bb7 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/MessageMappingReflectiveProcessorTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/MessageMappingReflectiveProcessorTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -38,7 +38,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Sebastien Deleuze
  */
-public class MessageMappingReflectiveProcessorTests {
+class MessageMappingReflectiveProcessorTests {
 
 	private final MessageMappingReflectiveProcessor processor = new MessageMappingReflectiveProcessor();
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/DestinationVariableMethodArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/DestinationVariableMethodArgumentResolverTests.java
index 0e2bff8990..8dccdee046 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/DestinationVariableMethodArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/DestinationVariableMethodArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -38,7 +38,7 @@ import static org.springframework.messaging.handler.annotation.MessagingPredicat
  * Test fixture for {@link DestinationVariableMethodArgumentResolver} tests.
  * @author Rossen Stoyanchev
  */
-public class DestinationVariableMethodArgumentResolverTests {
+class DestinationVariableMethodArgumentResolverTests {
 
 	private final DestinationVariableMethodArgumentResolver resolver =
 			new DestinationVariableMethodArgumentResolver(new DefaultConversionService());
@@ -48,13 +48,13 @@ public class DestinationVariableMethodArgumentResolverTests {
 
 
 	@Test
-	public void supportsParameter() {
+	void supportsParameter() {
 		assertThat(resolver.supportsParameter(this.resolvable.annot(destinationVar().noValue()).arg())).isTrue();
 		assertThat(resolver.supportsParameter(this.resolvable.annotNotPresent(DestinationVariable.class).arg())).isFalse();
 	}
 
 	@Test
-	public void resolveArgument() {
+	void resolveArgument() {
 
 		Map<String, Object> vars = new HashMap<>();
 		vars.put("foo", "bar");
@@ -71,7 +71,7 @@ public class DestinationVariableMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveArgumentNotFound() {
+	void resolveArgumentNotFound() {
 		Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).build();
 		assertThatExceptionOfType(MessageHandlingException.class).isThrownBy(() ->
 				resolveArgument(this.resolvable.annot(destinationVar().noValue()).arg(), message));
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/HeaderMethodArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/HeaderMethodArgumentResolverTests.java
index c5cff938c8..940d9a97f6 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/HeaderMethodArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/HeaderMethodArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,7 +43,7 @@ import static org.springframework.messaging.handler.annotation.MessagingPredicat
  * Test fixture for {@link HeaderMethodArgumentResolver} tests.
  * @author Rossen Stoyanchev
  */
-public class HeaderMethodArgumentResolverTests {
+class HeaderMethodArgumentResolverTests {
 
 	private HeaderMethodArgumentResolver resolver;
 
@@ -51,7 +51,6 @@ public class HeaderMethodArgumentResolverTests {
 
 
 	@BeforeEach
-	@SuppressWarnings("resource")
 	public void setup() {
 		GenericApplicationContext context = new GenericApplicationContext();
 		context.refresh();
@@ -60,13 +59,13 @@ public class HeaderMethodArgumentResolverTests {
 
 
 	@Test
-	public void supportsParameter() {
+	void supportsParameter() {
 		assertThat(this.resolver.supportsParameter(this.resolvable.annot(headerPlain()).arg())).isTrue();
 		assertThat(this.resolver.supportsParameter(this.resolvable.annotNotPresent(Header.class).arg())).isFalse();
 	}
 
 	@Test
-	public void resolveArgument() {
+	void resolveArgument() {
 		Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).setHeader("param1", "foo").build();
 		Object result = resolveArgument(this.resolvable.annot(headerPlain()).arg(), message);
 		assertThat(result).isEqualTo("foo");
@@ -81,7 +80,7 @@ public class HeaderMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveArgumentNativeHeaderAmbiguity() {
+	void resolveArgumentNativeHeaderAmbiguity() {
 		TestMessageHeaderAccessor headers = new TestMessageHeaderAccessor();
 		headers.setHeader("param1", "foo");
 		headers.setNativeHeader("param1", "native-foo");
@@ -95,21 +94,21 @@ public class HeaderMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveArgumentNotFound() {
+	void resolveArgumentNotFound() {
 		Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).build();
 		assertThatExceptionOfType(MessageHandlingException.class).isThrownBy(() ->
 				resolveArgument(this.resolvable.annot(headerPlain()).arg(), message));
 	}
 
 	@Test
-	public void resolveArgumentDefaultValue() {
+	void resolveArgumentDefaultValue() {
 		Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).build();
 		Object result = resolveArgument(this.resolvable.annot(header("name", "bar")).arg(), message);
 		assertThat(result).isEqualTo("bar");
 	}
 
 	@Test
-	public void resolveDefaultValueSystemProperty() {
+	void resolveDefaultValueSystemProperty() {
 		System.setProperty("systemProperty", "sysbar");
 		try {
 			Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).build();
@@ -123,7 +122,7 @@ public class HeaderMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveNameFromSystemProperty() {
+	void resolveNameFromSystemProperty() {
 		System.setProperty("systemProperty", "sysbar");
 		try {
 			Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).setHeader("sysbar", "foo").build();
@@ -137,7 +136,7 @@ public class HeaderMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveOptionalHeaderWithValue() {
+	void resolveOptionalHeaderWithValue() {
 		Message<String> message = MessageBuilder.withPayload("foo").setHeader("foo", "bar").build();
 		MethodParameter param = this.resolvable.annot(header("foo")).arg(Optional.class, String.class);
 		Object result = resolveArgument(param, message);
@@ -145,7 +144,7 @@ public class HeaderMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveOptionalHeaderAsEmpty() {
+	void resolveOptionalHeaderAsEmpty() {
 		Message<String> message = MessageBuilder.withPayload("foo").build();
 		MethodParameter param = this.resolvable.annot(header("foo")).arg(Optional.class, String.class);
 		Object result = resolveArgument(param, message);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/HeadersMethodArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/HeadersMethodArgumentResolverTests.java
index 91b60209b0..6c1b8a42b3 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/HeadersMethodArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/HeadersMethodArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -38,7 +38,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  * Test fixture for {@link HeadersMethodArgumentResolver} tests.
  * @author Rossen Stoyanchev
  */
-public class HeadersMethodArgumentResolverTests {
+class HeadersMethodArgumentResolverTests {
 
 	private final HeadersMethodArgumentResolver resolver = new HeadersMethodArgumentResolver();
 
@@ -49,7 +49,7 @@ public class HeadersMethodArgumentResolverTests {
 
 
 	@Test
-	public void supportsParameter() {
+	void supportsParameter() {
 
 		assertThat(this.resolver.supportsParameter(
 				this.resolvable.annotPresent(Headers.class).arg(Map.class, String.class, Object.class))).isTrue();
@@ -62,7 +62,6 @@ public class HeadersMethodArgumentResolverTests {
 	}
 
 	@Test
-	@SuppressWarnings("unchecked")
 	public void resolveArgumentAnnotated() {
 		MethodParameter param = this.resolvable.annotPresent(Headers.class).arg(Map.class, String.class, Object.class);
 		Map<String, Object> headers = resolveArgument(param);
@@ -70,25 +69,25 @@ public class HeadersMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveArgumentAnnotatedNotMap() {
+	void resolveArgumentAnnotatedNotMap() {
 		assertThatIllegalStateException().isThrownBy(() ->
 				resolveArgument(this.resolvable.annotPresent(Headers.class).arg(String.class)));
 	}
 
 	@Test
-	public void resolveArgumentMessageHeaders() {
+	void resolveArgumentMessageHeaders() {
 		MessageHeaders headers = resolveArgument(this.resolvable.arg(MessageHeaders.class));
 		assertThat(headers.get("foo")).isEqualTo("bar");
 	}
 
 	@Test
-	public void resolveArgumentMessageHeaderAccessor() {
+	void resolveArgumentMessageHeaderAccessor() {
 		MessageHeaderAccessor headers = resolveArgument(this.resolvable.arg(MessageHeaderAccessor.class));
 		assertThat(headers.getHeader("foo")).isEqualTo("bar");
 	}
 
 	@Test
-	public void resolveArgumentMessageHeaderAccessorSubclass() {
+	void resolveArgumentMessageHeaderAccessorSubclass() {
 		TestMessageHeaderAccessor headers = resolveArgument(this.resolvable.arg(TestMessageHeaderAccessor.class));
 		assertThat(headers.getHeader("foo")).isEqualTo("bar");
 	}
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/MessageMappingMessageHandlerTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/MessageMappingMessageHandlerTests.java
index 8c27048541..529d4d3357 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/MessageMappingMessageHandlerTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/MessageMappingMessageHandlerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -64,56 +64,56 @@ public class MessageMappingMessageHandlerTests {
 
 
 	@Test
-	public void handleString() {
+	void handleString() {
 		MessageMappingMessageHandler messsageHandler = initMesssageHandler();
 		messsageHandler.handleMessage(message("string", "abcdef")).block(Duration.ofSeconds(5));
 		verifyOutputContent(Collections.singletonList("abcdef::response"));
 	}
 
 	@Test
-	public void handleMonoString() {
+	void handleMonoString() {
 		MessageMappingMessageHandler messsageHandler = initMesssageHandler();
 		messsageHandler.handleMessage(message("monoString", "abcdef")).block(Duration.ofSeconds(5));
 		verifyOutputContent(Collections.singletonList("abcdef::response"));
 	}
 
 	@Test
-	public void handleFluxString() {
+	void handleFluxString() {
 		MessageMappingMessageHandler messsageHandler = initMesssageHandler();
 		messsageHandler.handleMessage(message("fluxString", "abc", "def", "ghi")).block(Duration.ofSeconds(5));
 		verifyOutputContent(Arrays.asList("abc::response", "def::response", "ghi::response"));
 	}
 
 	@Test
-	public void handleWithPlaceholderInMapping() {
+	void handleWithPlaceholderInMapping() {
 		MessageMappingMessageHandler messsageHandler = initMesssageHandler();
 		messsageHandler.handleMessage(message("path123", "abcdef")).block(Duration.ofSeconds(5));
 		verifyOutputContent(Collections.singletonList("abcdef::response"));
 	}
 
 	@Test
-	public void handleWithDestinationVariable() {
+	void handleWithDestinationVariable() {
 		MessageMappingMessageHandler messsageHandler = initMesssageHandler();
 		messsageHandler.handleMessage(message("destination.test", "abcdef")).block(Duration.ofSeconds(5));
 		verifyOutputContent(Collections.singletonList("test::abcdef::response"));
 	}
 
 	@Test
-	public void handleException() {
+	void handleException() {
 		MessageMappingMessageHandler messsageHandler = initMesssageHandler();
 		messsageHandler.handleMessage(message("exception", "abc")).block(Duration.ofSeconds(5));
 		verifyOutputContent(Collections.singletonList("rejected::handled"));
 	}
 
 	@Test
-	public void handleErrorSignal() {
+	void handleErrorSignal() {
 		MessageMappingMessageHandler messsageHandler = initMesssageHandler();
 		messsageHandler.handleMessage(message("errorSignal", "abc")).block(Duration.ofSeconds(5));
 		verifyOutputContent(Collections.singletonList("rejected::handled"));
 	}
 
 	@Test
-	public void unhandledExceptionShouldFlowThrough() {
+	void unhandledExceptionShouldFlowThrough() {
 
 		GenericMessage<?> message = new GenericMessage<>(new Object(),
 				Collections.singletonMap(DestinationPatternsMessageCondition.LOOKUP_DESTINATION_HEADER,
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/PayloadMethodArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/PayloadMethodArgumentResolverTests.java
index 7a78d3488c..88120a9133 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/PayloadMethodArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/PayloadMethodArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -56,7 +56,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Rossen Stoyanchev
  */
-public class PayloadMethodArgumentResolverTests {
+class PayloadMethodArgumentResolverTests {
 
 	private final List<Decoder<?>> decoders = new ArrayList<>();
 
@@ -64,7 +64,7 @@ public class PayloadMethodArgumentResolverTests {
 
 
 	@Test
-	public void supportsParameter() {
+	void supportsParameter() {
 
 		boolean useDefaultResolution = true;
 		PayloadMethodArgumentResolver resolver = createResolver(null, useDefaultResolution);
@@ -80,7 +80,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void emptyBodyWhenRequired() {
+	void emptyBodyWhenRequired() {
 		MethodParameter param = this.testMethod.arg(ResolvableType.forClassWithGenerics(Mono.class, String.class));
 		Mono<Object> mono = resolveValue(param, Mono.empty(), null);
 
@@ -93,13 +93,13 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void emptyBodyWhenNotRequired() {
+	void emptyBodyWhenNotRequired() {
 		MethodParameter param = this.testMethod.annotPresent(Payload.class).arg();
 		assertThat(this.<Object>resolveValue(param, Mono.empty(), null)).isNull();
 	}
 
 	@Test
-	public void stringMono() {
+	void stringMono() {
 		String body = "foo";
 		MethodParameter param = this.testMethod.arg(ResolvableType.forClassWithGenerics(Mono.class, String.class));
 		Mono<Object> mono = resolveValue(param,
@@ -109,7 +109,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void stringFlux() {
+	void stringFlux() {
 		List<String> body = Arrays.asList("foo", "bar");
 		ResolvableType type = ResolvableType.forClassWithGenerics(Flux.class, String.class);
 		MethodParameter param = this.testMethod.arg(type);
@@ -120,7 +120,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void string() {
+	void string() {
 		String body = "foo";
 		MethodParameter param = this.testMethod.annotNotPresent(Payload.class).arg(String.class);
 		Object value = resolveValue(param, Mono.just(toDataBuffer(body)), null);
@@ -129,7 +129,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void validateStringMono() {
+	void validateStringMono() {
 		TestValidator validator = new TestValidator();
 		ResolvableType type = ResolvableType.forClassWithGenerics(Mono.class, String.class);
 		MethodParameter param = this.testMethod.arg(type);
@@ -140,7 +140,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void validateStringFlux() {
+	void validateStringFlux() {
 		TestValidator validator = new TestValidator();
 		ResolvableType type = ResolvableType.forClassWithGenerics(Flux.class, String.class);
 		MethodParameter param = this.testMethod.arg(type);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/AnnotationExceptionHandlerMethodResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/AnnotationExceptionHandlerMethodResolverTests.java
index 6275974d13..3e65af69fd 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/AnnotationExceptionHandlerMethodResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/AnnotationExceptionHandlerMethodResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,32 +36,32 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  * @author Rossen Stoyanchev
  * @author Juergen Hoeller
  */
-public class AnnotationExceptionHandlerMethodResolverTests {
+class AnnotationExceptionHandlerMethodResolverTests {
 
 	private final AnnotationExceptionHandlerMethodResolver resolver =
 			new AnnotationExceptionHandlerMethodResolver(ExceptionController.class);
 
 
 	@Test
-	public void resolveMethodFromAnnotation() {
+	void resolveMethodFromAnnotation() {
 		IOException exception = new IOException();
 		assertThat(this.resolver.resolveMethod(exception).getName()).isEqualTo("handleIOException");
 	}
 
 	@Test
-	public void resolveMethodFromArgument() {
+	void resolveMethodFromArgument() {
 		IllegalArgumentException exception = new IllegalArgumentException();
 		assertThat(this.resolver.resolveMethod(exception).getName()).isEqualTo("handleIllegalArgumentException");
 	}
 
 	@Test
-	public void resolveMethodFromArgumentWithErrorType() {
+	void resolveMethodFromArgumentWithErrorType() {
 		AssertionError exception = new AssertionError();
 		assertThat(this.resolver.resolveMethod(new IllegalStateException(exception)).getName()).isEqualTo("handleAssertionError");
 	}
 
 	@Test
-	public void resolveMethodExceptionSubType() {
+	void resolveMethodExceptionSubType() {
 		IOException ioException = new FileNotFoundException();
 		assertThat(this.resolver.resolveMethod(ioException).getName()).isEqualTo("handleIOException");
 		SocketException bindException = new BindException();
@@ -69,38 +69,38 @@ public class AnnotationExceptionHandlerMethodResolverTests {
 	}
 
 	@Test
-	public void resolveMethodBestMatch() {
+	void resolveMethodBestMatch() {
 		SocketException exception = new SocketException();
 		assertThat(this.resolver.resolveMethod(exception).getName()).isEqualTo("handleSocketException");
 	}
 
 	@Test
-	public void resolveMethodNoMatch() {
+	void resolveMethodNoMatch() {
 		Exception exception = new Exception();
 		assertThat(this.resolver.resolveMethod(exception)).as("1st lookup").isNull();
 		assertThat(this.resolver.resolveMethod(exception)).as("2nd lookup from cache").isNull();
 	}
 
 	@Test
-	public void resolveMethodInherited() {
+	void resolveMethodInherited() {
 		IOException exception = new IOException();
 		assertThat(this.resolver.resolveMethod(exception).getName()).isEqualTo("handleIOException");
 	}
 
 	@Test
-	public void resolveMethodAgainstCause() {
+	void resolveMethodAgainstCause() {
 		IllegalStateException exception = new IllegalStateException(new IOException());
 		assertThat(this.resolver.resolveMethod(exception).getName()).isEqualTo("handleIOException");
 	}
 
 	@Test
-	public void ambiguousExceptionMapping() {
+	void ambiguousExceptionMapping() {
 		assertThatIllegalStateException().isThrownBy(() ->
 				new AnnotationExceptionHandlerMethodResolver(AmbiguousController.class));
 	}
 
 	@Test
-	public void noExceptionMapping() {
+	void noExceptionMapping() {
 		assertThatIllegalStateException().isThrownBy(() ->
 				new AnnotationExceptionHandlerMethodResolver(NoExceptionController.class));
 	}
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/DefaultMessageHandlerMethodFactoryTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/DefaultMessageHandlerMethodFactoryTests.java
index 3641cde73b..b934faf343 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/DefaultMessageHandlerMethodFactoryTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/DefaultMessageHandlerMethodFactoryTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,13 +49,13 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 /**
  * @author Stephane Nicoll
  */
-public class DefaultMessageHandlerMethodFactoryTests {
+class DefaultMessageHandlerMethodFactoryTests {
 
 	private final SampleBean sample = new SampleBean();
 
 
 	@Test
-	public void customConversion() throws Exception {
+	void customConversion() throws Exception {
 		DefaultMessageHandlerMethodFactory instance = createInstance();
 		GenericConversionService conversionService = new GenericConversionService();
 		conversionService.addConverter(SampleBean.class, String.class, source -> "foo bar");
@@ -70,7 +70,7 @@ public class DefaultMessageHandlerMethodFactoryTests {
 	}
 
 	@Test
-	public void customConversionServiceFailure() throws Exception {
+	void customConversionServiceFailure() {
 		DefaultMessageHandlerMethodFactory instance = createInstance();
 		GenericConversionService conversionService = new GenericConversionService();
 		assertThat(conversionService.canConvert(Integer.class, String.class)).as("conversion service should fail to convert payload").isFalse();
@@ -85,7 +85,7 @@ public class DefaultMessageHandlerMethodFactoryTests {
 	}
 
 	@Test
-	public void customMessageConverterFailure() throws Exception {
+	void customMessageConverterFailure() {
 		DefaultMessageHandlerMethodFactory instance = createInstance();
 		MessageConverter messageConverter = new ByteArrayMessageConverter();
 		instance.setMessageConverter(messageConverter);
@@ -99,7 +99,7 @@ public class DefaultMessageHandlerMethodFactoryTests {
 	}
 
 	@Test
-	public void customArgumentResolver() throws Exception {
+	void customArgumentResolver() throws Exception {
 		DefaultMessageHandlerMethodFactory instance = createInstance();
 		List<HandlerMethodArgumentResolver> customResolvers = new ArrayList<>();
 		customResolvers.add(new CustomHandlerMethodArgumentResolver());
@@ -114,7 +114,7 @@ public class DefaultMessageHandlerMethodFactoryTests {
 	}
 
 	@Test
-	public void overrideArgumentResolvers() throws Exception {
+	void overrideArgumentResolvers() throws Exception {
 		DefaultMessageHandlerMethodFactory instance = createInstance();
 		List<HandlerMethodArgumentResolver> customResolvers = new ArrayList<>();
 		customResolvers.add(new CustomHandlerMethodArgumentResolver());
@@ -138,7 +138,7 @@ public class DefaultMessageHandlerMethodFactoryTests {
 	}
 
 	@Test
-	public void noValidationByDefault() throws Exception {
+	void noValidationByDefault() throws Exception {
 		DefaultMessageHandlerMethodFactory instance = createInstance();
 		instance.afterPropertiesSet();
 
@@ -149,7 +149,7 @@ public class DefaultMessageHandlerMethodFactoryTests {
 	}
 
 	@Test
-	public void customValidation() throws Exception {
+	void customValidation() {
 		DefaultMessageHandlerMethodFactory instance = createInstance();
 		instance.setValidator(new Validator() {
 			@Override
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/DestinationVariableMethodArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/DestinationVariableMethodArgumentResolverTests.java
index 77335caf2e..04677c41f4 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/DestinationVariableMethodArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/DestinationVariableMethodArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -38,7 +38,7 @@ import static org.springframework.messaging.handler.annotation.MessagingPredicat
  *
  * @author Brian Clozel
  */
-public class DestinationVariableMethodArgumentResolverTests {
+class DestinationVariableMethodArgumentResolverTests {
 
 	private final DestinationVariableMethodArgumentResolver resolver =
 			new DestinationVariableMethodArgumentResolver(new DefaultConversionService());
@@ -48,13 +48,13 @@ public class DestinationVariableMethodArgumentResolverTests {
 
 
 	@Test
-	public void supportsParameter() {
+	void supportsParameter() {
 		assertThat(resolver.supportsParameter(this.resolvable.annot(destinationVar().noValue()).arg())).isTrue();
 		assertThat(resolver.supportsParameter(this.resolvable.annotNotPresent(DestinationVariable.class).arg())).isFalse();
 	}
 
 	@Test
-	public void resolveArgument() throws Exception {
+	void resolveArgument() throws Exception {
 
 		Map<String, Object> vars = new HashMap<>();
 		vars.put("foo", "bar");
@@ -73,7 +73,7 @@ public class DestinationVariableMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveArgumentNotFound() throws Exception {
+	void resolveArgumentNotFound() {
 		Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).build();
 		assertThatExceptionOfType(MessageHandlingException.class).isThrownBy(() ->
 				this.resolver.resolveArgument(this.resolvable.annot(destinationVar().noValue()).arg(), message));
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolverTests.java
index 8db7f97f17..713d9600fd 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -45,7 +45,7 @@ import static org.springframework.messaging.handler.annotation.MessagingPredicat
  * @author Juergen Hoeller
  * @since 4.0
  */
-public class HeaderMethodArgumentResolverTests {
+class HeaderMethodArgumentResolverTests {
 
 	private HeaderMethodArgumentResolver resolver;
 
@@ -53,7 +53,6 @@ public class HeaderMethodArgumentResolverTests {
 
 
 	@BeforeEach
-	@SuppressWarnings("resource")
 	public void setup() {
 		GenericApplicationContext context = new GenericApplicationContext();
 		context.refresh();
@@ -62,13 +61,13 @@ public class HeaderMethodArgumentResolverTests {
 
 
 	@Test
-	public void supportsParameter() {
+	void supportsParameter() {
 		assertThat(this.resolver.supportsParameter(this.resolvable.annot(headerPlain()).arg())).isTrue();
 		assertThat(this.resolver.supportsParameter(this.resolvable.annotNotPresent(Header.class).arg())).isFalse();
 	}
 
 	@Test
-	public void resolveArgument() throws Exception {
+	void resolveArgument() throws Exception {
 		Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).setHeader("param1", "foo").build();
 		Object result = this.resolver.resolveArgument(this.resolvable.annot(headerPlain()).arg(), message);
 		assertThat(result).isEqualTo("foo");
@@ -83,7 +82,7 @@ public class HeaderMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveArgumentNativeHeaderAmbiguity() throws Exception {
+	void resolveArgumentNativeHeaderAmbiguity() throws Exception {
 		TestMessageHeaderAccessor headers = new TestMessageHeaderAccessor();
 		headers.setHeader("param1", "foo");
 		headers.setNativeHeader("param1", "native-foo");
@@ -97,21 +96,21 @@ public class HeaderMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveArgumentNotFound() throws Exception {
+	void resolveArgumentNotFound() {
 		Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).build();
 		assertThatExceptionOfType(MessageHandlingException.class).isThrownBy(() ->
 				this.resolver.resolveArgument(this.resolvable.annot(headerPlain()).arg(), message));
 	}
 
 	@Test
-	public void resolveArgumentDefaultValue() throws Exception {
+	void resolveArgumentDefaultValue() throws Exception {
 		Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).build();
 		Object result = this.resolver.resolveArgument(this.resolvable.annot(header("name", "bar")).arg(), message);
 		assertThat(result).isEqualTo("bar");
 	}
 
 	@Test
-	public void resolveDefaultValueSystemProperty() throws Exception {
+	void resolveDefaultValueSystemProperty() throws Exception {
 		System.setProperty("systemProperty", "sysbar");
 		try {
 			Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).build();
@@ -125,7 +124,7 @@ public class HeaderMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveNameFromSystemProperty() throws Exception {
+	void resolveNameFromSystemProperty() throws Exception {
 		System.setProperty("systemProperty", "sysbar");
 		try {
 			Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).setHeader("sysbar", "foo").build();
@@ -139,7 +138,7 @@ public class HeaderMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveOptionalHeaderWithValue() throws Exception {
+	void resolveOptionalHeaderWithValue() throws Exception {
 		Message<String> message = MessageBuilder.withPayload("foo").setHeader("foo", "bar").build();
 		MethodParameter param = this.resolvable.annot(header("foo")).arg(Optional.class, String.class);
 		Object result = resolver.resolveArgument(param, message);
@@ -147,7 +146,7 @@ public class HeaderMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveOptionalHeaderAsEmpty() throws Exception {
+	void resolveOptionalHeaderAsEmpty() throws Exception {
 		Message<String> message = MessageBuilder.withPayload("foo").build();
 		MethodParameter param = this.resolvable.annot(header("foo")).arg(Optional.class, String.class);
 		Object result = resolver.resolveArgument(param, message);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/HeadersMethodArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/HeadersMethodArgumentResolverTests.java
index 0a30c4af46..b52202495e 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/HeadersMethodArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/HeadersMethodArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,7 +39,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  * @author Rossen Stoyanchev
  * @since 4.0
  */
-public class HeadersMethodArgumentResolverTests {
+class HeadersMethodArgumentResolverTests {
 
 	private final HeadersMethodArgumentResolver resolver = new HeadersMethodArgumentResolver();
 
@@ -50,7 +50,7 @@ public class HeadersMethodArgumentResolverTests {
 
 
 	@Test
-	public void supportsParameter() {
+	void supportsParameter() {
 
 		assertThat(this.resolver.supportsParameter(
 				this.resolvable.annotPresent(Headers.class).arg(Map.class, String.class, Object.class))).isTrue();
@@ -63,7 +63,7 @@ public class HeadersMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveArgumentAnnotated() throws Exception {
+	void resolveArgumentAnnotated() throws Exception {
 		MethodParameter param = this.resolvable.annotPresent(Headers.class).arg(Map.class, String.class, Object.class);
 		Object resolved = this.resolver.resolveArgument(param, this.message);
 
@@ -75,13 +75,13 @@ public class HeadersMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveArgumentAnnotatedNotMap() throws Exception {
+	void resolveArgumentAnnotatedNotMap() {
 		assertThatIllegalStateException().isThrownBy(() ->
 				this.resolver.resolveArgument(this.resolvable.annotPresent(Headers.class).arg(String.class), this.message));
 	}
 
 	@Test
-	public void resolveArgumentMessageHeaders() throws Exception {
+	void resolveArgumentMessageHeaders() throws Exception {
 		Object resolved = this.resolver.resolveArgument(this.resolvable.arg(MessageHeaders.class), this.message);
 
 		boolean condition = resolved instanceof MessageHeaders;
@@ -91,7 +91,7 @@ public class HeadersMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveArgumentMessageHeaderAccessor() throws Exception {
+	void resolveArgumentMessageHeaderAccessor() throws Exception {
 		MethodParameter param = this.resolvable.arg(MessageHeaderAccessor.class);
 		Object resolved = this.resolver.resolveArgument(param, this.message);
 
@@ -102,7 +102,7 @@ public class HeadersMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveArgumentMessageHeaderAccessorSubclass() throws Exception {
+	void resolveArgumentMessageHeaderAccessorSubclass() throws Exception {
 		MethodParameter param = this.resolvable.arg(TestMessageHeaderAccessor.class);
 		Object resolved = this.resolver.resolveArgument(param, this.message);
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/MessageMethodArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/MessageMethodArgumentResolverTests.java
index ac24e12703..26cb249124 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/MessageMethodArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/MessageMethodArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,7 +42,7 @@ import static org.mockito.Mockito.mock;
  * @author Stephane Nicoll
  * @author Juergen Hoeller
  */
-public class MessageMethodArgumentResolverTests {
+class MessageMethodArgumentResolverTests {
 
 	private MessageConverter converter = mock();
 
@@ -52,14 +52,14 @@ public class MessageMethodArgumentResolverTests {
 
 
 	@BeforeEach
-	public void setup() throws Exception {
+	void setup() throws Exception {
 		this.method = getClass().getDeclaredMethod("handle",
 				Message.class, Message.class, Message.class, Message.class, ErrorMessage.class, Message.class);
 	}
 
 
 	@Test
-	public void resolveWithPayloadTypeAsWildcard() throws Exception {
+	void resolveWithPayloadTypeAsWildcard() throws Exception {
 		Message<String> message = MessageBuilder.withPayload("test").build();
 		MethodParameter parameter = new MethodParameter(this.method, 0);
 
@@ -68,7 +68,7 @@ public class MessageMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveWithMatchingPayloadType() throws Exception {
+	void resolveWithMatchingPayloadType() throws Exception {
 		Message<Integer> message = MessageBuilder.withPayload(123).build();
 		MethodParameter parameter = new MethodParameter(this.method, 1);
 
@@ -77,7 +77,7 @@ public class MessageMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveWithPayloadTypeSubclass() throws Exception {
+	void resolveWithPayloadTypeSubclass() throws Exception {
 		Message<Integer> message = MessageBuilder.withPayload(123).build();
 		MethodParameter parameter = new MethodParameter(this.method, 2);
 
@@ -86,7 +86,7 @@ public class MessageMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveWithConversion() throws Exception {
+	void resolveWithConversion() throws Exception {
 		Message<String> message = MessageBuilder.withPayload("test").build();
 		MethodParameter parameter = new MethodParameter(this.method, 1);
 
@@ -101,7 +101,7 @@ public class MessageMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveWithConversionNoMatchingConverter() throws Exception {
+	void resolveWithConversionNoMatchingConverter() {
 		Message<String> message = MessageBuilder.withPayload("test").build();
 		MethodParameter parameter = new MethodParameter(this.method, 1);
 
@@ -113,7 +113,7 @@ public class MessageMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveWithConversionEmptyPayload() throws Exception {
+	void resolveWithConversionEmptyPayload() {
 		Message<String> message = MessageBuilder.withPayload("").build();
 		MethodParameter parameter = new MethodParameter(this.method, 1);
 
@@ -126,7 +126,7 @@ public class MessageMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveWithPayloadTypeUpperBound() throws Exception {
+	void resolveWithPayloadTypeUpperBound() throws Exception {
 		Message<Integer> message = MessageBuilder.withPayload(123).build();
 		MethodParameter parameter = new MethodParameter(this.method, 3);
 
@@ -135,7 +135,7 @@ public class MessageMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveWithPayloadTypeOutOfBound() throws Exception {
+	void resolveWithPayloadTypeOutOfBound() {
 		Message<Locale> message = MessageBuilder.withPayload(Locale.getDefault()).build();
 		MethodParameter parameter = new MethodParameter(this.method, 3);
 
@@ -147,7 +147,7 @@ public class MessageMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveMessageSubclassMatch() throws Exception {
+	void resolveMessageSubclassMatch() throws Exception {
 		ErrorMessage message = new ErrorMessage(new UnsupportedOperationException());
 		MethodParameter parameter = new MethodParameter(this.method, 4);
 
@@ -156,7 +156,7 @@ public class MessageMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveWithMessageSubclassAndPayloadWildcard() throws Exception {
+	void resolveWithMessageSubclassAndPayloadWildcard() throws Exception {
 		ErrorMessage message = new ErrorMessage(new UnsupportedOperationException());
 		MethodParameter parameter = new MethodParameter(this.method, 0);
 
@@ -165,7 +165,7 @@ public class MessageMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveWithWrongMessageType() throws Exception {
+	void resolveWithWrongMessageType() {
 		UnsupportedOperationException ex = new UnsupportedOperationException();
 		Message<? extends Throwable> message = new GenericMessage<Throwable>(ex);
 		MethodParameter parameter = new MethodParameter(this.method, 4);
@@ -178,7 +178,7 @@ public class MessageMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveWithPayloadTypeAsWildcardAndNoConverter() throws Exception {
+	void resolveWithPayloadTypeAsWildcardAndNoConverter() throws Exception {
 		this.resolver = new MessageMethodArgumentResolver();
 
 		Message<String> message = MessageBuilder.withPayload("test").build();
@@ -189,7 +189,7 @@ public class MessageMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveWithConversionNeededButNoConverter() throws Exception {
+	void resolveWithConversionNeededButNoConverter() {
 		this.resolver = new MessageMethodArgumentResolver();
 
 		Message<String> message = MessageBuilder.withPayload("test").build();
@@ -203,7 +203,7 @@ public class MessageMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveWithConversionEmptyPayloadButNoConverter() throws Exception {
+	void resolveWithConversionEmptyPayloadButNoConverter() {
 		this.resolver = new MessageMethodArgumentResolver();
 
 		Message<String> message = MessageBuilder.withPayload("").build();
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/PayloadMethodArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/PayloadMethodArgumentResolverTests.java
index 89d37a5107..ba37697603 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/PayloadMethodArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/PayloadMethodArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -50,7 +50,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  * @author Brian Clozel
  * @author Stephane Nicoll
  */
-public class PayloadMethodArgumentResolverTests {
+class PayloadMethodArgumentResolverTests {
 
 	private PayloadMethodArgumentResolver resolver;
 
@@ -72,7 +72,7 @@ public class PayloadMethodArgumentResolverTests {
 
 
 	@BeforeEach
-	public void setup() throws Exception {
+	void setup() throws Exception {
 		this.resolver = new PayloadMethodArgumentResolver(new StringMessageConverter(), testValidator());
 
 		Method payloadMethod = PayloadMethodArgumentResolverTests.class.getDeclaredMethod(
@@ -91,7 +91,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void supportsParameter() {
+	void supportsParameter() {
 		assertThat(this.resolver.supportsParameter(this.paramAnnotated)).isTrue();
 		assertThat(this.resolver.supportsParameter(this.paramNotAnnotated)).isTrue();
 
@@ -103,7 +103,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveRequired() throws Exception {
+	void resolveRequired() throws Exception {
 		Message<?> message = MessageBuilder.withPayload("ABC".getBytes()).build();
 		Object actual = this.resolver.resolveArgument(paramAnnotated, message);
 
@@ -111,7 +111,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveRequiredEmpty() {
+	void resolveRequiredEmpty() {
 		Message<?> message = MessageBuilder.withPayload("").build();
 		 // required but empty
 		assertThatExceptionOfType(MethodArgumentNotValidException.class)
@@ -119,7 +119,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveRequiredEmptyNonAnnotatedParameter() {
+	void resolveRequiredEmptyNonAnnotatedParameter() {
 		Message<?> message = MessageBuilder.withPayload("").build();
 		// required but empty
 		assertThatExceptionOfType(MethodArgumentNotValidException.class)
@@ -127,7 +127,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveNotRequired() throws Exception {
+	void resolveNotRequired() throws Exception {
 		Message<?> emptyByteArrayMessage = MessageBuilder.withPayload(new byte[0]).build();
 		assertThat(this.resolver.resolveArgument(this.paramAnnotatedNotRequired, emptyByteArrayMessage)).isNull();
 
@@ -143,7 +143,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveOptionalTarget() throws Exception {
+	void resolveOptionalTarget() throws Exception {
 		Message<?> message = MessageBuilder.withPayload("ABC".getBytes()).build();
 		Object actual = this.resolver.resolveArgument(paramOptional, message);
 
@@ -151,7 +151,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveOptionalSource() throws Exception {
+	void resolveOptionalSource() throws Exception {
 		Message<?> message = MessageBuilder.withPayload(Optional.of("ABC".getBytes())).build();
 		Object actual = this.resolver.resolveArgument(paramAnnotated, message);
 
@@ -159,7 +159,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveNonConvertibleParam() {
+	void resolveNonConvertibleParam() {
 		Message<?> notEmptyMessage = MessageBuilder.withPayload(123).build();
 
 		assertThatExceptionOfType(MessageConversionException.class)
@@ -168,7 +168,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveSpelExpressionNotSupported() {
+	void resolveSpelExpressionNotSupported() {
 		Message<?> message = MessageBuilder.withPayload("ABC".getBytes()).build();
 
 		assertThatIllegalStateException()
@@ -176,13 +176,13 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveValidation() throws Exception {
+	void resolveValidation() throws Exception {
 		Message<?> message = MessageBuilder.withPayload("ABC".getBytes()).build();
 		this.resolver.resolveArgument(this.paramValidated, message);
 	}
 
 	@Test
-	public void resolveFailValidation() {
+	void resolveFailValidation() {
 		// See testValidator()
 		Message<?> message = MessageBuilder.withPayload("invalidValue".getBytes()).build();
 
@@ -191,7 +191,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveFailValidationNoConversionNecessary() {
+	void resolveFailValidationNoConversionNecessary() {
 		Message<?> message = MessageBuilder.withPayload("invalidValue").build();
 
 		assertThatExceptionOfType(MethodArgumentNotValidException.class)
@@ -199,7 +199,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveNonAnnotatedParameter() throws Exception {
+	void resolveNonAnnotatedParameter() throws Exception {
 		Message<?> notEmptyMessage = MessageBuilder.withPayload("ABC".getBytes()).build();
 		assertThat(this.resolver.resolveArgument(this.paramNotAnnotated, notEmptyMessage)).isEqualTo("ABC");
 
@@ -209,7 +209,7 @@ public class PayloadMethodArgumentResolverTests {
 	}
 
 	@Test
-	public void resolveNonAnnotatedParameterFailValidation() {
+	void resolveNonAnnotatedParameterFailValidation() {
 		// See testValidator()
 		Message<?> message = MessageBuilder.withPayload("invalidValue".getBytes()).build();
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/InvocableHandlerMethodTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/InvocableHandlerMethodTests.java
index 3a7d204fc2..f3b008c9ea 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/InvocableHandlerMethodTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/InvocableHandlerMethodTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,7 +37,7 @@ import static org.mockito.Mockito.mock;
  *
  * @author Rossen Stoyanchev
  */
-public class InvocableHandlerMethodTests {
+class InvocableHandlerMethodTests {
 
 	private final Message<?> message = mock();
 
@@ -45,7 +45,7 @@ public class InvocableHandlerMethodTests {
 
 
 	@Test
-	public void resolveArg() throws Exception {
+	void resolveArg() throws Exception {
 		this.resolvers.addResolver(new StubArgumentResolver(99));
 		this.resolvers.addResolver(new StubArgumentResolver("value"));
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
@@ -59,7 +59,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void resolveNoArgValue() throws Exception {
+	void resolveNoArgValue() throws Exception {
 		this.resolvers.addResolver(new StubArgumentResolver(Integer.class));
 		this.resolvers.addResolver(new StubArgumentResolver(String.class));
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
@@ -71,7 +71,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void cannotResolveArg() throws Exception {
+	void cannotResolveArg() {
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
 		assertThatExceptionOfType(MethodArgumentResolutionException.class)
 			.isThrownBy(() -> invoke(new Handler(), method))
@@ -79,7 +79,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void resolveProvidedArg() throws Exception {
+	void resolveProvidedArg() throws Exception {
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
 		Object value = invoke(new Handler(), method, 99, "value");
 
@@ -89,7 +89,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void resolveProvidedArgFirst() throws Exception {
+	void resolveProvidedArgFirst() throws Exception {
 		this.resolvers.addResolver(new StubArgumentResolver(1));
 		this.resolvers.addResolver(new StubArgumentResolver("value1"));
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
@@ -99,7 +99,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void exceptionInResolvingArg() throws Exception {
+	void exceptionInResolvingArg() {
 		this.resolvers.addResolver(new ExceptionRaisingArgumentResolver());
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
 		assertThatIllegalArgumentException().isThrownBy(() ->
@@ -108,7 +108,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void illegalArgumentException() throws Exception {
+	void illegalArgumentException() {
 		this.resolvers.addResolver(new StubArgumentResolver(Integer.class, "__not_an_int__"));
 		this.resolvers.addResolver(new StubArgumentResolver("value"));
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
@@ -123,7 +123,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void invocationTargetException() throws Exception {
+	void invocationTargetException() {
 		Handler handler = new Handler();
 		Method method = ResolvableMethod.on(Handler.class).argTypes(Throwable.class).resolveMethod();
 		RuntimeException runtimeException = new RuntimeException("error");
@@ -146,7 +146,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test  // Based on SPR-13917 (spring-web)
-	public void invocationErrorMessage() throws Exception {
+	public void invocationErrorMessage() {
 		this.resolvers.addResolver(new StubArgumentResolver(double.class));
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0.0)).method();
 		assertThatIllegalStateException().isThrownBy(() ->
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/MethodMessageHandlerTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/MethodMessageHandlerTests.java
index f1c38cb479..5fb96aaa9c 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/MethodMessageHandlerTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/MethodMessageHandlerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,7 +18,6 @@ package org.springframework.messaging.handler.invocation;
 
 import java.lang.reflect.Method;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Comparator;
 import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
@@ -50,7 +49,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  * @author Brian Clozel
  * @author Rossen Stoyanchev
  */
-public class MethodMessageHandlerTests {
+class MethodMessageHandlerTests {
 
 	private static final String DESTINATION_HEADER = "destination";
 
@@ -60,9 +59,9 @@ public class MethodMessageHandlerTests {
 
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 
-		List<String> destinationPrefixes = Arrays.asList("/test");
+		List<String> destinationPrefixes = List.of("/test");
 
 		this.messageHandler = new TestMethodMessageHandler();
 		this.messageHandler.setApplicationContext(new StaticApplicationContext());
@@ -74,13 +73,13 @@ public class MethodMessageHandlerTests {
 	}
 
 	@Test
-	public void duplicateMapping() {
+	void duplicateMapping() {
 		assertThatIllegalStateException().isThrownBy(() ->
 				this.messageHandler.registerHandler(new DuplicateMappingsController()));
 	}
 
 	@Test
-	public void registeredMappings() {
+	void registeredMappings() {
 
 		Map<String, HandlerMethod> handlerMethods = this.messageHandler.getHandlerMethods();
 
@@ -89,7 +88,7 @@ public class MethodMessageHandlerTests {
 	}
 
 	@Test
-	public void patternMatch() throws Exception {
+	void patternMatch() throws Exception {
 
 		Method method = this.testController.getClass().getMethod("handlerPathMatchWildcard");
 		this.messageHandler.registerHandlerMethod(this.testController, method, "/handlerPathMatch*");
@@ -100,7 +99,7 @@ public class MethodMessageHandlerTests {
 	}
 
 	@Test
-	public void bestMatch() throws Exception {
+	void bestMatch() throws Exception {
 
 		Method method = this.testController.getClass().getMethod("bestMatch");
 		this.messageHandler.registerHandlerMethod(this.testController, method, "/bestmatch/{foo}/path");
@@ -114,7 +113,7 @@ public class MethodMessageHandlerTests {
 	}
 
 	@Test
-	public void argumentResolution() {
+	void argumentResolution() {
 
 		this.messageHandler.handleMessage(toDestination("/test/handlerArgumentResolver"));
 
@@ -123,7 +122,7 @@ public class MethodMessageHandlerTests {
 	}
 
 	@Test
-	public void handleException() {
+	void handleException() {
 
 		this.messageHandler.handleMessage(toDestination("/test/handlerThrowsExc"));
 
@@ -205,8 +204,7 @@ public class MethodMessageHandlerTests {
 
 		@Override
 		protected List<? extends HandlerMethodReturnValueHandler> initReturnValueHandlers() {
-			List<HandlerMethodReturnValueHandler> handlers = new ArrayList<>(getCustomReturnValueHandlers());
-			return handlers;
+			return new ArrayList<>(getCustomReturnValueHandlers());
 		}
 
 		@Override
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/reactive/EncoderMethodReturnValueHandlerTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/reactive/EncoderMethodReturnValueHandlerTests.java
index bc79a0a889..729db0a4e1 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/reactive/EncoderMethodReturnValueHandlerTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/reactive/EncoderMethodReturnValueHandlerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -38,7 +38,7 @@ import static org.springframework.messaging.handler.invocation.ResolvableMethod.
  *
  * @author Rossen Stoyanchev
  */
-public class EncoderMethodReturnValueHandlerTests {
+class EncoderMethodReturnValueHandlerTests {
 
 	private final TestEncoderMethodReturnValueHandler handler = new TestEncoderMethodReturnValueHandler(
 			Collections.singletonList(CharSequenceEncoder.textPlainOnly()),
@@ -48,7 +48,7 @@ public class EncoderMethodReturnValueHandlerTests {
 
 
 	@Test
-	public void stringReturnValue() {
+	void stringReturnValue() {
 		MethodParameter parameter = on(TestController.class).resolveReturnType(String.class);
 		this.handler.handleReturnValue("foo", parameter, this.message).block();
 		Flux<String> result = this.handler.getContentAsStrings();
@@ -57,7 +57,7 @@ public class EncoderMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void objectReturnValue() {
+	void objectReturnValue() {
 		MethodParameter parameter = on(TestController.class).resolveReturnType(Object.class);
 		this.handler.handleReturnValue("foo", parameter, this.message).block();
 		Flux<String> result = this.handler.getContentAsStrings();
@@ -66,7 +66,7 @@ public class EncoderMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void fluxStringReturnValue() {
+	void fluxStringReturnValue() {
 		MethodParameter parameter = on(TestController.class).resolveReturnType(Flux.class, String.class);
 		this.handler.handleReturnValue(Flux.just("foo", "bar"), parameter, this.message).block();
 		Flux<String> result = this.handler.getContentAsStrings();
@@ -75,7 +75,7 @@ public class EncoderMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void fluxObjectReturnValue() {
+	void fluxObjectReturnValue() {
 		MethodParameter parameter = on(TestController.class).resolveReturnType(Flux.class, Object.class);
 		this.handler.handleReturnValue(Flux.just("foo", "bar"), parameter, this.message).block();
 		Flux<String> result = this.handler.getContentAsStrings();
@@ -84,7 +84,7 @@ public class EncoderMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void voidReturnValue() {
+	void voidReturnValue() {
 		testVoidReturnType(null, on(TestController.class).resolveReturnType(void.class));
 		testVoidReturnType(Mono.empty(), on(TestController.class).resolveReturnType(Mono.class, Void.class));
 		testVoidReturnType(Completable.complete(), on(TestController.class).resolveReturnType(Completable.class));
@@ -97,7 +97,7 @@ public class EncoderMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void noEncoder() {
+	void noEncoder() {
 		MethodParameter parameter = on(TestController.class).resolveReturnType(Object.class);
 		StepVerifier.create(this.handler.handleReturnValue(new Object(), parameter, this.message))
 				.expectErrorMessage("No encoder for java.lang.Object, current value type is class java.lang.Object")
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/reactive/InvocableHandlerMethodTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/reactive/InvocableHandlerMethodTests.java
index bb88912cac..528f6bd29a 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/reactive/InvocableHandlerMethodTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/reactive/InvocableHandlerMethodTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -44,7 +44,7 @@ import static org.mockito.Mockito.mock;
  * @author Rossen Stoyanchev
  * @author Juergen Hoeller
  */
-public class InvocableHandlerMethodTests {
+class InvocableHandlerMethodTests {
 
 	private final Message<?> message = mock();
 
@@ -52,7 +52,7 @@ public class InvocableHandlerMethodTests {
 
 
 	@Test
-	public void resolveArg() {
+	void resolveArg() {
 		this.resolvers.add(new StubArgumentResolver(99));
 		this.resolvers.add(new StubArgumentResolver("value"));
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
@@ -66,7 +66,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void resolveNoArgValue() {
+	void resolveNoArgValue() {
 		this.resolvers.add(new StubArgumentResolver(Integer.class));
 		this.resolvers.add(new StubArgumentResolver(String.class));
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
@@ -78,7 +78,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void cannotResolveArg() {
+	void cannotResolveArg() {
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
 		assertThatExceptionOfType(MethodArgumentResolutionException.class).isThrownBy(() ->
 				invokeAndBlock(new Handler(), method))
@@ -86,7 +86,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void resolveProvidedArg() {
+	void resolveProvidedArg() {
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
 		Object value = invokeAndBlock(new Handler(), method, 99, "value");
 
@@ -96,7 +96,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void resolveProvidedArgFirst() {
+	void resolveProvidedArgFirst() {
 		this.resolvers.add(new StubArgumentResolver(1));
 		this.resolvers.add(new StubArgumentResolver("value1"));
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
@@ -106,7 +106,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void exceptionInResolvingArg() {
+	void exceptionInResolvingArg() {
 		this.resolvers.add(new InvocableHandlerMethodTests.ExceptionRaisingArgumentResolver());
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
 		assertThatIllegalArgumentException().isThrownBy(() ->
@@ -114,7 +114,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void illegalArgumentException() {
+	void illegalArgumentException() {
 		this.resolvers.add(new StubArgumentResolver(Integer.class, "__not_an_int__"));
 		this.resolvers.add(new StubArgumentResolver("value"));
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0, "")).method();
@@ -129,7 +129,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void invocationTargetException() {
+	void invocationTargetException() {
 		Method method = ResolvableMethod.on(Handler.class).argTypes(Throwable.class).resolveMethod();
 
 		Throwable expected = new Throwable("error");
@@ -138,7 +138,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void voidMethod() {
+	void voidMethod() {
 		this.resolvers.add(new StubArgumentResolver(double.class, 5.25));
 		Method method = ResolvableMethod.on(Handler.class).mockCall(c -> c.handle(0.0d)).method();
 		Handler handler = new Handler();
@@ -151,7 +151,7 @@ public class InvocableHandlerMethodTests {
 	}
 
 	@Test
-	public void voidMonoMethod() {
+	void voidMonoMethod() {
 		Method method = ResolvableMethod.on(Handler.class).mockCall(Handler::handleAsync).method();
 		Handler handler = new Handler();
 		Object value = invokeAndBlock(handler, method);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/reactive/MethodMessageHandlerTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/reactive/MethodMessageHandlerTests.java
index 78680e7c47..9dafcb7436 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/reactive/MethodMessageHandlerTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/invocation/reactive/MethodMessageHandlerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -52,17 +52,17 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  * Unit tests for {@link AbstractMethodMessageHandler}.
  * @author Rossen Stoyanchev
  */
-public class MethodMessageHandlerTests {
+class MethodMessageHandlerTests {
 
 
 	@Test
-	public void duplicateMapping() {
+	void duplicateMapping() {
 		assertThatIllegalStateException().isThrownBy(() ->
 				initMethodMessageHandler(DuplicateMappingsController.class));
 	}
 
 	@Test
-	public void registeredMappings() {
+	void registeredMappings() {
 		TestMethodMessageHandler messageHandler = initMethodMessageHandler(TestController.class);
 		Map<String, HandlerMethod> mappings = messageHandler.getHandlerMethods();
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultMetadataExtractorTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultMetadataExtractorTests.java
index 68753e2464..b9b33e87ec 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultMetadataExtractorTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultMetadataExtractorTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -53,7 +53,7 @@ import static org.springframework.util.MimeTypeUtils.TEXT_XML;
  */
 class DefaultMetadataExtractorTests {
 
-	private static MimeType COMPOSITE_METADATA =
+	private static final MimeType COMPOSITE_METADATA =
 			MimeTypeUtils.parseMimeType(WellKnownMimeType.MESSAGE_RSOCKET_COMPOSITE_METADATA.getString());
 
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultRSocketRequesterBuilderTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultRSocketRequesterBuilderTests.java
index 286e9a75b6..ce5a8755c9 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultRSocketRequesterBuilderTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultRSocketRequesterBuilderTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -64,7 +64,7 @@ import static org.mockito.Mockito.verify;
  *
  * @author Brian Clozel
  */
-public class DefaultRSocketRequesterBuilderTests {
+class DefaultRSocketRequesterBuilderTests {
 
 	private ClientTransport transport = mock();
 
@@ -74,14 +74,13 @@ public class DefaultRSocketRequesterBuilderTests {
 
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 		given(this.transport.connect()).willReturn(Mono.just(this.connection));
 		given(this.transport.maxFrameLength()).willReturn(16777215);
 	}
 
 
 	@Test
-	@SuppressWarnings("unchecked")
 	public void rsocketConnectorConfigurer() {
 		Consumer<RSocketStrategies.Builder> strategiesConfigurer = mock();
 		RSocketRequester.builder()
@@ -96,7 +95,7 @@ public class DefaultRSocketRequesterBuilderTests {
 	}
 
 	@Test
-	public void defaultDataMimeType() {
+	void defaultDataMimeType() {
 		RSocketRequester requester = RSocketRequester.builder().transport(this.transport);
 
 		assertThat(requester.dataMimeType())
@@ -105,7 +104,7 @@ public class DefaultRSocketRequesterBuilderTests {
 	}
 
 	@Test
-	public void defaultDataMimeTypeWithCustomDecoderRegistered() {
+	void defaultDataMimeTypeWithCustomDecoderRegistered() {
 		RSocketStrategies strategies = RSocketStrategies.builder()
 				.decoder(new TestJsonDecoder(MimeTypeUtils.APPLICATION_JSON))
 				.build();
@@ -120,7 +119,7 @@ public class DefaultRSocketRequesterBuilderTests {
 	}
 
 	@Test
-	public void dataMimeTypeExplicitlySet() {
+	void dataMimeTypeExplicitlySet() {
 		RSocketRequester requester = RSocketRequester.builder()
 				.dataMimeType(MimeTypeUtils.APPLICATION_JSON)
 				.transport(this.transport);
@@ -132,7 +131,7 @@ public class DefaultRSocketRequesterBuilderTests {
 	}
 
 	@Test
-	public void mimeTypesCannotBeChangedAtRSocketConnectorLevel() {
+	void mimeTypesCannotBeChangedAtRSocketConnectorLevel() {
 		MimeType dataMimeType = MimeTypeUtils.APPLICATION_JSON;
 		MimeType metaMimeType = MimeTypeUtils.parseMimeType(WellKnownMimeType.MESSAGE_RSOCKET_ROUTING.getString());
 
@@ -154,7 +153,7 @@ public class DefaultRSocketRequesterBuilderTests {
 	}
 
 	@Test
-	public void setupRoute() {
+	void setupRoute() {
 		RSocketRequester requester = RSocketRequester.builder()
 				.dataMimeType(MimeTypeUtils.TEXT_PLAIN)
 				.metadataMimeType(MimeTypeUtils.TEXT_PLAIN)
@@ -169,7 +168,7 @@ public class DefaultRSocketRequesterBuilderTests {
 	}
 
 	@Test
-	public void setupWithAsyncValues() {
+	void setupWithAsyncValues() {
 
 		Mono<String> asyncMeta1 = Mono.delay(Duration.ofMillis(1)).map(aLong -> "Async Metadata 1");
 		Mono<String> asyncMeta2 = Mono.delay(Duration.ofMillis(1)).map(aLong -> "Async Metadata 2");
@@ -199,7 +198,7 @@ public class DefaultRSocketRequesterBuilderTests {
 	}
 
 	@Test
-	public void frameDecoderMatchesDataBufferFactory() throws Exception {
+	void frameDecoderMatchesDataBufferFactory() throws Exception {
 		testPayloadDecoder(new NettyDataBufferFactory(ByteBufAllocator.DEFAULT), PayloadDecoder.ZERO_COPY);
 		testPayloadDecoder(DefaultDataBufferFactory.sharedInstance, PayloadDecoder.DEFAULT);
 	}
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultRSocketRequesterTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultRSocketRequesterTests.java
index 9c6281aa18..7d6d9d683b 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultRSocketRequesterTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultRSocketRequesterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -51,7 +51,7 @@ import static org.springframework.util.MimeTypeUtils.TEXT_PLAIN;
  *
  * @author Rossen Stoyanchev
  */
-public class DefaultRSocketRequesterTests {
+class DefaultRSocketRequesterTests {
 
 	private static final Duration MILLIS_10 = Duration.ofMillis(10);
 
@@ -64,14 +64,14 @@ public class DefaultRSocketRequesterTests {
 
 
 	@BeforeEach
-	public void setUp() {
+	void setUp() {
 		this.rsocket = new TestRSocket();
 		this.requester = RSocketRequester.wrap(this.rsocket, TEXT_PLAIN, TEXT_PLAIN, this.strategies);
 	}
 
 
 	@Test
-	public void sendMono() {
+	void sendMono() {
 
 		// data(Object)
 		testSendMono(spec -> spec.data("bodyA"), "bodyA");
@@ -95,7 +95,7 @@ public class DefaultRSocketRequesterTests {
 	}
 
 	@Test
-	public void sendFlux() {
+	void sendFlux() {
 		String[] values = new String[] {"bodyA", "bodyB", "bodyC"};
 		Flux<String> stringFlux = Flux.fromArray(values).delayElements(MILLIS_10);
 
@@ -132,7 +132,7 @@ public class DefaultRSocketRequesterTests {
 	}
 
 	@Test
-	public void sendWithoutData() {
+	void sendWithoutData() {
 		this.requester.route("toA").send().block(Duration.ofSeconds(5));
 
 		assertThat(this.rsocket.getSavedMethodName()).isEqualTo("fireAndForget");
@@ -141,7 +141,7 @@ public class DefaultRSocketRequesterTests {
 	}
 
 	@Test
-	public void testSendWithAsyncMetadata() {
+	void testSendWithAsyncMetadata() {
 
 		MimeType compositeMimeType =
 				MimeTypeUtils.parseMimeType(WellKnownMimeType.MESSAGE_RSOCKET_COMPOSITE_METADATA.getString());
@@ -171,7 +171,7 @@ public class DefaultRSocketRequesterTests {
 	}
 
 	@Test
-	public void retrieveMono() {
+	void retrieveMono() {
 		String value = "bodyA";
 		this.rsocket.setPayloadMonoToReturn(Mono.delay(MILLIS_10).thenReturn(toPayload(value)));
 		Mono<String> response = this.requester.route("").data("").retrieveMono(String.class);
@@ -181,7 +181,7 @@ public class DefaultRSocketRequesterTests {
 	}
 
 	@Test
-	public void retrieveMonoVoid() {
+	void retrieveMonoVoid() {
 		AtomicBoolean consumed = new AtomicBoolean();
 		Mono<Payload> mono = Mono.delay(MILLIS_10).thenReturn(toPayload("bodyA")).doOnSuccess(p -> consumed.set(true));
 		this.rsocket.setPayloadMonoToReturn(mono);
@@ -192,7 +192,7 @@ public class DefaultRSocketRequesterTests {
 	}
 
 	@Test
-	public void retrieveMonoWithoutData() {
+	void retrieveMonoWithoutData() {
 		this.requester.route("toA").retrieveMono(String.class).block(Duration.ofSeconds(5));
 
 		assertThat(this.rsocket.getSavedMethodName()).isEqualTo("requestResponse");
@@ -201,7 +201,7 @@ public class DefaultRSocketRequesterTests {
 	}
 
 	@Test
-	public void retrieveFlux() {
+	void retrieveFlux() {
 		String[] values = new String[] {"bodyA", "bodyB", "bodyC"};
 		this.rsocket.setPayloadFluxToReturn(Flux.fromArray(values).delayElements(MILLIS_10).map(this::toPayload));
 		Flux<String> response = this.requester.route("").data("").retrieveFlux(String.class);
@@ -211,7 +211,7 @@ public class DefaultRSocketRequesterTests {
 	}
 
 	@Test
-	public void retrieveFluxVoid() {
+	void retrieveFluxVoid() {
 		AtomicBoolean consumed = new AtomicBoolean();
 		Flux<Payload> flux = Flux.just("bodyA", "bodyB")
 				.delayElements(MILLIS_10).map(this::toPayload).doOnComplete(() -> consumed.set(true));
@@ -223,7 +223,7 @@ public class DefaultRSocketRequesterTests {
 	}
 
 	@Test
-	public void retrieveFluxWithoutData() {
+	void retrieveFluxWithoutData() {
 		this.requester.route("toA").retrieveFlux(String.class).blockLast(Duration.ofSeconds(5));
 
 		assertThat(this.rsocket.getSavedMethodName()).isEqualTo("requestStream");
@@ -232,7 +232,7 @@ public class DefaultRSocketRequesterTests {
 	}
 
 	@Test
-	public void fluxToMonoIsRejected() {
+	void fluxToMonoIsRejected() {
 		assertThatIllegalStateException()
 				.isThrownBy(() -> this.requester.route("").data(Flux.just("a", "b")).retrieveMono(String.class))
 				.withMessage("No RSocket interaction with Flux request and Mono response.");
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultRSocketStrategiesTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultRSocketStrategiesTests.java
index 47941d610a..82565b8692 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultRSocketStrategiesTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultRSocketStrategiesTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -108,7 +108,6 @@ class DefaultRSocketStrategiesTests {
 	}
 
 	@Test
-	@SuppressWarnings("unchecked")
 	void applyMetadataExtractors() {
 		Consumer<MetadataExtractorRegistry> consumer = mock();
 		RSocketStrategies.builder().metadataExtractorRegistry(consumer).build();
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/LeakAwareNettyDataBufferFactory.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/LeakAwareNettyDataBufferFactory.java
index 42bcfd35a7..5ff3ac04df 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/LeakAwareNettyDataBufferFactory.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/LeakAwareNettyDataBufferFactory.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -106,7 +106,7 @@ public class LeakAwareNettyDataBufferFactory extends NettyDataBufferFactory {
 	}
 
 
-	private static record DataBufferLeakInfo(DataBuffer dataBuffer, AssertionError error) {
+	private record DataBufferLeakInfo(DataBuffer dataBuffer, AssertionError error) {
 	}
 
 }
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/MetadataEncoderTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/MetadataEncoderTests.java
index 8a16aa8d29..1e573a1644 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/MetadataEncoderTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/MetadataEncoderTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -47,7 +47,7 @@ import static org.assertj.core.api.Assertions.assertThatThrownBy;
  */
 class MetadataEncoderTests {
 
-	private static MimeType COMPOSITE_METADATA =
+	private static final MimeType COMPOSITE_METADATA =
 			MimeTypeUtils.parseMimeType(WellKnownMimeType.MESSAGE_RSOCKET_COMPOSITE_METADATA.getString());
 
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/PayloadUtilsTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/PayloadUtilsTests.java
index 2fb1571290..be4416a488 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/PayloadUtilsTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/PayloadUtilsTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,7 +43,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class PayloadUtilsTests {
 
-	private LeakAwareNettyDataBufferFactory nettyBufferFactory =
+	private final LeakAwareNettyDataBufferFactory nettyBufferFactory =
 			new LeakAwareNettyDataBufferFactory(PooledByteBufAllocator.DEFAULT);
 
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketBufferLeakTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketBufferLeakTests.java
index 6696034fad..a7778e73fa 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketBufferLeakTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketBufferLeakTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -157,7 +157,7 @@ class RSocketBufferLeakTests {
 	}
 
 	@Test
-	public void echoChannel() {
+	void echoChannel() {
 		Flux<String> result = requester.route("echo-channel")
 				.data(Flux.range(1, 10).map(i -> "Hello " + i), String.class)
 				.retrieveFlux(String.class);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketClientToServerIntegrationTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketClientToServerIntegrationTests.java
index 267ca44066..0fe26cddd8 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketClientToServerIntegrationTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketClientToServerIntegrationTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -58,7 +58,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Rossen Stoyanchev
  * @author Sebastien Deleuze
  */
-public class RSocketClientToServerIntegrationTests {
+class RSocketClientToServerIntegrationTests {
 
 	private static final MimeType FOO_MIME_TYPE = MimeTypeUtils.parseMimeType("messaging/x.foo");
 
@@ -103,7 +103,7 @@ public class RSocketClientToServerIntegrationTests {
 
 
 	@Test
-	public void fireAndForget() {
+	void fireAndForget() {
 		Flux.range(1, 3)
 				.delayElements(Duration.ofMillis(10))
 				.concatMap(i -> requester.route("receive").data("Hello " + i).send())
@@ -123,7 +123,7 @@ public class RSocketClientToServerIntegrationTests {
 	}
 
 	@Test
-	public void echo() {
+	void echo() {
 		Flux<String> result = Flux.range(1, 3).concatMap(i ->
 				requester.route("echo").data("Hello " + i).retrieveMono(String.class));
 
@@ -134,7 +134,7 @@ public class RSocketClientToServerIntegrationTests {
 	}
 
 	@Test
-	public void echoAsync() {
+	void echoAsync() {
 		Flux<String> result = Flux.range(1, 3).concatMap(i ->
 				requester.route("echo-async").data("Hello " + i).retrieveMono(String.class));
 
@@ -145,7 +145,7 @@ public class RSocketClientToServerIntegrationTests {
 	}
 
 	@Test
-	public void echoStream() {
+	void echoStream() {
 		Flux<String> result = requester.route("echo-stream").data("Hello").retrieveFlux(String.class);
 
 		StepVerifier.create(result)
@@ -155,7 +155,7 @@ public class RSocketClientToServerIntegrationTests {
 	}
 
 	@Test
-	public void echoChannel() {
+	void echoChannel() {
 		Flux<String> result = requester.route("echo-channel")
 				.data(Flux.range(1, 10).map(i -> "Hello " + i), String.class)
 				.retrieveFlux(String.class);
@@ -173,7 +173,7 @@ public class RSocketClientToServerIntegrationTests {
 	}
 
 	@Test
-	public void metadataPush() {
+	void metadataPush() {
 		Flux.just("bar", "baz")
 				.delayElements(Duration.ofMillis(10))
 				.concatMap(s -> requester.route("foo-updates").metadata(s, FOO_MIME_TYPE).sendMetadata())
@@ -192,19 +192,19 @@ public class RSocketClientToServerIntegrationTests {
 	}
 
 	@Test
-	public void voidReturnValue() {
+	void voidReturnValue() {
 		Mono<String> result = requester.route("void-return-value").data("Hello").retrieveMono(String.class);
 		StepVerifier.create(result).expectComplete().verify(Duration.ofSeconds(5));
 	}
 
 	@Test
-	public void voidReturnValueFromExceptionHandler() {
+	void voidReturnValueFromExceptionHandler() {
 		Mono<String> result = requester.route("void-return-value").data("bad").retrieveMono(String.class);
 		StepVerifier.create(result).expectComplete().verify(Duration.ofSeconds(5));
 	}
 
 	@Test
-	public void handleWithThrownException() {
+	void handleWithThrownException() {
 		Mono<String> result = requester.route("thrown-exception").data("a").retrieveMono(String.class);
 		StepVerifier.create(result)
 				.expectNext("Invalid input error handled")
@@ -213,7 +213,7 @@ public class RSocketClientToServerIntegrationTests {
 	}
 
 	@Test
-	public void handleWithErrorSignal() {
+	void handleWithErrorSignal() {
 		Mono<String> result = requester.route("error-signal").data("a").retrieveMono(String.class);
 		StepVerifier.create(result)
 				.expectNext("Invalid input error handled")
@@ -222,7 +222,7 @@ public class RSocketClientToServerIntegrationTests {
 	}
 
 	@Test
-	public void noMatchingRoute() {
+	void noMatchingRoute() {
 		Mono<String> result = requester.route("invalid").data("anything").retrieveMono(String.class);
 		StepVerifier.create(result)
 				.expectErrorMessage("No handler for destination 'invalid'")
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketServerToClientIntegrationTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketServerToClientIntegrationTests.java
index 3bf659f20c..57857693b4 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketServerToClientIntegrationTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/RSocketServerToClientIntegrationTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -121,7 +121,7 @@ class RSocketServerToClientIntegrationTests {
 
 
 	@Controller
-	@SuppressWarnings({"unused", "NullableProblems"})
+	@SuppressWarnings("unused")
 	static class ServerController {
 
 		// Must be initialized by @Test method...
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/annotation/support/RSocketFrameTypeMessageConditionTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/annotation/support/RSocketFrameTypeMessageConditionTests.java
index 715ba8f43f..688f0209f0 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/annotation/support/RSocketFrameTypeMessageConditionTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/annotation/support/RSocketFrameTypeMessageConditionTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,14 +33,14 @@ import static org.springframework.messaging.rsocket.annotation.support.RSocketFr
  * Unit tests for {@link RSocketFrameTypeMessageCondition}.
  * @author Rossen Stoyanchev
  */
-public class RSocketFrameTypeMessageConditionTests {
+class RSocketFrameTypeMessageConditionTests {
 
 	private static final RSocketFrameTypeMessageCondition FNF_RR_CONDITION =
 			new RSocketFrameTypeMessageCondition(FrameType.REQUEST_FNF, FrameType.REQUEST_RESPONSE);
 
 
 	@Test
-	public void getMatchingCondition() {
+	void getMatchingCondition() {
 		Message<?> message = message(FrameType.REQUEST_RESPONSE);
 		RSocketFrameTypeMessageCondition actual = FNF_RR_CONDITION.getMatchingCondition(message);
 
@@ -49,7 +49,7 @@ public class RSocketFrameTypeMessageConditionTests {
 	}
 
 	@Test
-	public void getMatchingConditionEmpty() {
+	void getMatchingConditionEmpty() {
 		Message<?> message = message(FrameType.REQUEST_RESPONSE);
 		RSocketFrameTypeMessageCondition actual = EMPTY_CONDITION.getMatchingCondition(message);
 
@@ -57,7 +57,7 @@ public class RSocketFrameTypeMessageConditionTests {
 	}
 
 	@Test
-	public void combine() {
+	void combine() {
 
 		assertThat(EMPTY_CONDITION.combine(CONNECT_CONDITION).getFrameTypes())
 				.containsExactly(FrameType.SETUP, FrameType.METADATA_PUSH);
@@ -67,7 +67,7 @@ public class RSocketFrameTypeMessageConditionTests {
 	}
 
 	@Test
-	public void compareTo() {
+	void compareTo() {
 		Message<byte[]> message = message(null);
 		assertThat(condition(FrameType.SETUP).compareTo(condition(FrameType.SETUP), message)).isEqualTo(0);
 		assertThat(condition(FrameType.SETUP).compareTo(condition(FrameType.METADATA_PUSH), message)).isEqualTo(0);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/annotation/support/RSocketMessageHandlerTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/annotation/support/RSocketMessageHandlerTests.java
index 2c00e831b1..5844083c32 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/annotation/support/RSocketMessageHandlerTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/annotation/support/RSocketMessageHandlerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -56,10 +56,10 @@ import static org.assertj.core.api.Assertions.assertThatThrownBy;
  * @author Rossen Stoyanchev
  * @since 5.2
  */
-public class RSocketMessageHandlerTests {
+class RSocketMessageHandlerTests {
 
 	@Test
-	public void getRSocketStrategies() {
+	void getRSocketStrategies() {
 		RSocketMessageHandler handler = new RSocketMessageHandler();
 		handler.setDecoders(Collections.singletonList(new ByteArrayDecoder()));
 		handler.setEncoders(Collections.singletonList(new ByteArrayEncoder()));
@@ -77,7 +77,7 @@ public class RSocketMessageHandlerTests {
 	}
 
 	@Test
-	public void setRSocketStrategies() {
+	void setRSocketStrategies() {
 		RSocketStrategies strategies = RSocketStrategies.builder()
 				.encoder(new ByteArrayEncoder())
 				.decoder(new ByteArrayDecoder())
@@ -97,7 +97,7 @@ public class RSocketMessageHandlerTests {
 	}
 
 	@Test
-	public void getRSocketStrategiesReflectsCurrentState() {
+	void getRSocketStrategiesReflectsCurrentState() {
 
 		RSocketMessageHandler handler = new RSocketMessageHandler();
 
@@ -132,7 +132,7 @@ public class RSocketMessageHandlerTests {
 	}
 
 	@Test
-	public void metadataExtractorWithExplicitlySetDecoders() {
+	void metadataExtractorWithExplicitlySetDecoders() {
 		DefaultMetadataExtractor extractor = new DefaultMetadataExtractor(StringDecoder.allMimeTypes());
 
 		RSocketMessageHandler handler = new RSocketMessageHandler();
@@ -145,7 +145,7 @@ public class RSocketMessageHandlerTests {
 	}
 
 	@Test
-	public void mappings() {
+	void mappings() {
 		testMapping(new SimpleController(), "path");
 		testMapping(new TypeLevelMappingController(), "base.path");
 		testMapping(new HandleAllController());
@@ -175,7 +175,7 @@ public class RSocketMessageHandlerTests {
 	}
 
 	@Test
-	public void rejectConnectMappingMethodsThatCanReply() {
+	void rejectConnectMappingMethodsThatCanReply() {
 
 		RSocketMessageHandler handler = new RSocketMessageHandler();
 		handler.setHandlers(Collections.singletonList(new InvalidConnectMappingController()));
@@ -196,7 +196,7 @@ public class RSocketMessageHandlerTests {
 	}
 
 	@Test
-	public void ignoreFireAndForgetToHandlerThatCanReply() {
+	void ignoreFireAndForgetToHandlerThatCanReply() {
 
 		InteractionMismatchController controller = new InteractionMismatchController();
 
@@ -217,7 +217,7 @@ public class RSocketMessageHandlerTests {
 	}
 
 	@Test
-	public void rejectRequestResponseToStreamingHandler() {
+	void rejectRequestResponseToStreamingHandler() {
 
 		RSocketMessageHandler handler = new RSocketMessageHandler();
 		handler.setHandlers(Collections.singletonList(new InteractionMismatchController()));
@@ -238,7 +238,7 @@ public class RSocketMessageHandlerTests {
 	}
 
 	@Test
-	public void handleNoMatch() {
+	void handleNoMatch() {
 
 		testHandleNoMatch(FrameType.SETUP);
 		testHandleNoMatch(FrameType.METADATA_PUSH);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/DestinationVariableArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/DestinationVariableArgumentResolverTests.java
index 3dd093a628..2189195add 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/DestinationVariableArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/DestinationVariableArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,7 +30,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Unit tests for {@link DestinationVariableArgumentResolver}.
  * @author Rossen Stoyanchev
  */
-public class DestinationVariableArgumentResolverTests extends RSocketServiceArgumentResolverTestSupport {
+class DestinationVariableArgumentResolverTests extends RSocketServiceArgumentResolverTestSupport {
 
 	@Override
 	protected RSocketServiceArgumentResolver initResolver() {
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/MetadataArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/MetadataArgumentResolverTests.java
index 894cba5a3d..03d0426f1f 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/MetadataArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/MetadataArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,7 +31,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Unit tests for {@link MetadataArgumentResolver}.
  * @author Rossen Stoyanchev
  */
-public class MetadataArgumentResolverTests extends RSocketServiceArgumentResolverTestSupport {
+class MetadataArgumentResolverTests extends RSocketServiceArgumentResolverTestSupport {
 
 	@Override
 	protected RSocketServiceArgumentResolver initResolver() {
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/PayloadArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/PayloadArgumentResolverTests.java
index d585d64bac..210f8aa067 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/PayloadArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/PayloadArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,7 +34,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  * Unit tests for {@link PayloadArgumentResolver}.
  * @author Rossen Stoyanchev
  */
-public class PayloadArgumentResolverTests extends RSocketServiceArgumentResolverTestSupport {
+class PayloadArgumentResolverTests extends RSocketServiceArgumentResolverTestSupport {
 
 	@Override
 	protected RSocketServiceArgumentResolver initResolver() {
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/RSocketRequestValuesTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/RSocketRequestValuesTests.java
index defffb15e5..02039639a7 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/RSocketRequestValuesTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/RSocketRequestValuesTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,7 +30,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  * Unit tests for {@link RSocketRequestValues}.
  * @author Rossen Stoyanchev
  */
-public class RSocketRequestValuesTests {
+class RSocketRequestValuesTests {
 
 	@Test
 	void route() {
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/RSocketServiceMethodTests.java b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/RSocketServiceMethodTests.java
index 3292e6f1dd..9718d608e6 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/RSocketServiceMethodTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/rsocket/service/RSocketServiceMethodTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,7 +39,7 @@ import static org.springframework.util.MimeTypeUtils.TEXT_PLAIN;
  *
  * @author Rossen Stoyanchev
  */
-public class RSocketServiceMethodTests {
+class RSocketServiceMethodTests {
 
 	private TestRSocket rsocket;
 
@@ -47,7 +47,7 @@ public class RSocketServiceMethodTests {
 
 
 	@BeforeEach
-	public void setUp() {
+	void setUp() {
 		this.rsocket = new TestRSocket();
 		RSocketRequester requester = RSocketRequester.wrap(this.rsocket, TEXT_PLAIN, TEXT_PLAIN, RSocketStrategies.create());
 		this.proxyFactory = RSocketServiceProxyFactory.builder(requester).build();
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpAttributesContextHolderTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpAttributesContextHolderTests.java
index c42e857392..44fcda0d7b 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpAttributesContextHolderTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpAttributesContextHolderTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,25 +42,25 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  * @author Rossen Stoyanchev
  * @since 4.1
  */
-public class SimpAttributesContextHolderTests {
+class SimpAttributesContextHolderTests {
 
 	private SimpAttributes simpAttributes;
 
 
 	@BeforeEach
-	public void setUp() {
+	void setUp() {
 		Map<String, Object> map = new ConcurrentHashMap<>();
 		this.simpAttributes = new SimpAttributes("session1", map);
 	}
 
 	@AfterEach
-	public void tearDown() {
+	void tearDown() {
 		SimpAttributesContextHolder.resetAttributes();
 	}
 
 
 	@Test
-	public void resetAttributes() {
+	void resetAttributes() {
 		SimpAttributesContextHolder.setAttributes(this.simpAttributes);
 		assertThat(SimpAttributesContextHolder.getAttributes()).isSameAs(this.simpAttributes);
 
@@ -69,7 +69,7 @@ public class SimpAttributesContextHolderTests {
 	}
 
 	@Test
-	public void getAttributes() {
+	void getAttributes() {
 		assertThat(SimpAttributesContextHolder.getAttributes()).isNull();
 
 		SimpAttributesContextHolder.setAttributes(this.simpAttributes);
@@ -77,7 +77,7 @@ public class SimpAttributesContextHolderTests {
 	}
 
 	@Test
-	public void setAttributes() {
+	void setAttributes() {
 		SimpAttributesContextHolder.setAttributes(this.simpAttributes);
 		assertThat(SimpAttributesContextHolder.getAttributes()).isSameAs(this.simpAttributes);
 
@@ -86,7 +86,7 @@ public class SimpAttributesContextHolderTests {
 	}
 
 	@Test
-	public void setAttributesFromMessage() {
+	void setAttributesFromMessage() {
 
 		String sessionId = "session1";
 		ConcurrentHashMap<String, Object> map = new ConcurrentHashMap<>();
@@ -107,14 +107,14 @@ public class SimpAttributesContextHolderTests {
 	}
 
 	@Test
-	public void setAttributesFromMessageWithMissingSessionId() {
+	void setAttributesFromMessageWithMissingSessionId() {
 		assertThatIllegalStateException().isThrownBy(() ->
 				SimpAttributesContextHolder.setAttributesFromMessage(new GenericMessage<Object>("")))
 			.withMessageStartingWith("No session id in");
 	}
 
 	@Test
-	public void setAttributesFromMessageWithMissingSessionAttributes() {
+	void setAttributesFromMessageWithMissingSessionAttributes() {
 		SimpMessageHeaderAccessor headerAccessor = SimpMessageHeaderAccessor.create();
 		headerAccessor.setSessionId("session1");
 		Message<?> message = MessageBuilder.createMessage("", headerAccessor.getMessageHeaders());
@@ -124,13 +124,13 @@ public class SimpAttributesContextHolderTests {
 	}
 
 	@Test
-	public void currentAttributes() {
+	void currentAttributes() {
 		SimpAttributesContextHolder.setAttributes(this.simpAttributes);
 		assertThat(SimpAttributesContextHolder.currentAttributes()).isSameAs(this.simpAttributes);
 	}
 
 	@Test
-	public void currentAttributesNone() {
+	void currentAttributesNone() {
 		assertThatIllegalStateException().isThrownBy(SimpAttributesContextHolder::currentAttributes)
 			.withMessageStartingWith("No thread-bound SimpAttributes found");
 	}
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpAttributesTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpAttributesTests.java
index 5c70590fd1..8bfa07d56c 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpAttributesTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpAttributesTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,7 +33,7 @@ import static org.mockito.Mockito.verify;
  * @author Rossen Stoyanchev
  * @since 4.1
  */
-public class SimpAttributesTests {
+class SimpAttributesTests {
 
 	private final Map<String, Object> map = new ConcurrentHashMap<>();
 
@@ -41,7 +41,7 @@ public class SimpAttributesTests {
 
 
 	@Test
-	public void getAttribute() {
+	void getAttribute() {
 		this.simpAttributes.setAttribute("name1", "value1");
 
 		assertThat(this.simpAttributes.getAttribute("name1")).isEqualTo("value1");
@@ -49,7 +49,7 @@ public class SimpAttributesTests {
 	}
 
 	@Test
-	public void getAttributeNames() {
+	void getAttributeNames() {
 		this.simpAttributes.setAttribute("name1", "value1");
 		this.simpAttributes.setAttribute("name2", "value1");
 		this.simpAttributes.setAttribute("name3", "value1");
@@ -59,7 +59,7 @@ public class SimpAttributesTests {
 	}
 
 	@Test
-	public void registerDestructionCallback() {
+	void registerDestructionCallback() {
 		Runnable callback = mock();
 		this.simpAttributes.registerDestructionCallback("name1", callback);
 
@@ -68,7 +68,7 @@ public class SimpAttributesTests {
 	}
 
 	@Test
-	public void registerDestructionCallbackAfterSessionCompleted() {
+	void registerDestructionCallbackAfterSessionCompleted() {
 		this.simpAttributes.sessionCompleted();
 		assertThatIllegalStateException()
 				.isThrownBy(() -> this.simpAttributes.registerDestructionCallback("name1", mock()))
@@ -76,7 +76,7 @@ public class SimpAttributesTests {
 	}
 
 	@Test
-	public void removeDestructionCallback() {
+	void removeDestructionCallback() {
 		Runnable callback1 = mock();
 		Runnable callback2 = mock();
 		this.simpAttributes.registerDestructionCallback("name1", callback1);
@@ -86,12 +86,12 @@ public class SimpAttributesTests {
 	}
 
 	@Test
-	public void getSessionMutex() {
+	void getSessionMutex() {
 		assertThat(this.simpAttributes.getSessionMutex()).isSameAs(this.map);
 	}
 
 	@Test
-	public void getSessionMutexExplicit() {
+	void getSessionMutexExplicit() {
 		Object mutex = new Object();
 		this.simpAttributes.setAttribute(SimpAttributes.SESSION_MUTEX_NAME, mutex);
 
@@ -99,7 +99,7 @@ public class SimpAttributesTests {
 	}
 
 	@Test
-	public void sessionCompleted() {
+	void sessionCompleted() {
 		Runnable callback1 = mock();
 		Runnable callback2 = mock();
 		this.simpAttributes.registerDestructionCallback("name1", callback1);
@@ -112,7 +112,7 @@ public class SimpAttributesTests {
 	}
 
 	@Test
-	public void sessionCompletedIsIdempotent() {
+	void sessionCompletedIsIdempotent() {
 		Runnable callback1 = mock();
 		this.simpAttributes.registerDestructionCallback("name1", callback1);
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpMessageHeaderAccessorTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpMessageHeaderAccessorTests.java
index 9e0b434af5..af1c5adbf1 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpMessageHeaderAccessorTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpMessageHeaderAccessorTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -32,23 +32,23 @@ import static org.mockito.Mockito.mock;
  *
  * @author Rossen Stoyanchev
  */
-public class SimpMessageHeaderAccessorTests {
+class SimpMessageHeaderAccessorTests {
 
 
 	@Test
-	public void getShortLogMessage() {
+	void getShortLogMessage() {
 		assertThat(SimpMessageHeaderAccessor.create().getShortLogMessage("p"))
 				.isEqualTo("MESSAGE session=null payload=p");
 	}
 
 	@Test
-	public void getLogMessageWithValuesSet() {
+	void getLogMessageWithValuesSet() {
 		SimpMessageHeaderAccessor accessor = SimpMessageHeaderAccessor.create();
 		accessor.setDestination("/destination");
 		accessor.setSubscriptionId("subscription");
 		accessor.setSessionId("session");
 		accessor.setUser(new TestPrincipal("user"));
-		accessor.setSessionAttributes(Collections.<String, Object>singletonMap("key", "value"));
+		accessor.setSessionAttributes(Collections.singletonMap("key", "value"));
 
 		assertThat(accessor.getShortLogMessage("p"))
 				.isEqualTo(("MESSAGE destination=/destination subscriptionId=subscription " +
@@ -56,13 +56,13 @@ public class SimpMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void getDetailedLogMessageWithValuesSet() {
+	void getDetailedLogMessageWithValuesSet() {
 		SimpMessageHeaderAccessor accessor = SimpMessageHeaderAccessor.create();
 		accessor.setDestination("/destination");
 		accessor.setSubscriptionId("subscription");
 		accessor.setSessionId("session");
 		accessor.setUser(new TestPrincipal("user"));
-		accessor.setSessionAttributes(Collections.<String, Object>singletonMap("key", "value"));
+		accessor.setSessionAttributes(Collections.singletonMap("key", "value"));
 		accessor.setNativeHeader("nativeKey", "nativeValue");
 
 		assertThat(accessor.getDetailedLogMessage("p"))
@@ -72,7 +72,7 @@ public class SimpMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void userChangeCallback() {
+	void userChangeCallback() {
 		UserCallback userCallback = new UserCallback();
 		SimpMessageHeaderAccessor accessor = SimpMessageHeaderAccessor.create();
 		accessor.setUserChangeCallback(userCallback);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpMessageTypeMessageConditionTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpMessageTypeMessageConditionTests.java
index 6cc84346d5..2cf45353b4 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpMessageTypeMessageConditionTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpMessageTypeMessageConditionTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,10 +28,10 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Rossen Stoyanchev
  */
-public class SimpMessageTypeMessageConditionTests {
+class SimpMessageTypeMessageConditionTests {
 
 	@Test
-	public void combine() {
+	void combine() {
 		SimpMessageType messageType = SimpMessageType.MESSAGE;
 		SimpMessageType subscribeType = SimpMessageType.SUBSCRIBE;
 
@@ -46,7 +46,7 @@ public class SimpMessageTypeMessageConditionTests {
 	}
 
 	@Test
-	public void getMatchingCondition() {
+	void getMatchingCondition() {
 		Message<?> message = message(SimpMessageType.MESSAGE);
 		SimpMessageTypeMessageCondition condition = condition(SimpMessageType.MESSAGE);
 		SimpMessageTypeMessageCondition actual = condition.getMatchingCondition(message);
@@ -56,7 +56,7 @@ public class SimpMessageTypeMessageConditionTests {
 	}
 
 	@Test
-	public void getMatchingConditionNoMessageType() {
+	void getMatchingConditionNoMessageType() {
 		Message<?> message = message(null);
 		SimpMessageTypeMessageCondition condition = condition(SimpMessageType.MESSAGE);
 
@@ -64,7 +64,7 @@ public class SimpMessageTypeMessageConditionTests {
 	}
 
 	@Test
-	public void compareTo() {
+	void compareTo() {
 		Message<byte[]> message = message(null);
 		assertThat(condition(SimpMessageType.MESSAGE).compareTo(condition(SimpMessageType.MESSAGE), message)).isEqualTo(0);
 		assertThat(condition(SimpMessageType.MESSAGE).compareTo(condition(SimpMessageType.SUBSCRIBE), message)).isEqualTo(0);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpMessagingTemplateTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpMessagingTemplateTests.java
index 37dd3b56f4..49ea557921 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpMessagingTemplateTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpMessagingTemplateTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,6 @@
 
 package org.springframework.messaging.simp;
 
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -43,7 +42,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  *
  * @author Rossen Stoyanchev
  */
-public class SimpMessagingTemplateTests {
+class SimpMessagingTemplateTests {
 
 	private SimpMessagingTemplate messagingTemplate;
 
@@ -51,14 +50,14 @@ public class SimpMessagingTemplateTests {
 
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 		this.messageChannel = new StubMessageChannel();
 		this.messagingTemplate = new SimpMessagingTemplate(this.messageChannel);
 	}
 
 
 	@Test
-	public void convertAndSendToUser() {
+	void convertAndSendToUser() {
 		this.messagingTemplate.convertAndSendToUser("joe", "/queue/foo", "data");
 		List<Message<byte[]>> messages = this.messageChannel.getMessages();
 
@@ -74,7 +73,7 @@ public class SimpMessagingTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendToUserWithEncoding() {
+	void convertAndSendToUserWithEncoding() {
 		this.messagingTemplate.convertAndSendToUser("https://joe.openid.example.org/", "/queue/foo", "data");
 		List<Message<byte[]>> messages = this.messageChannel.getMessages();
 
@@ -94,8 +93,8 @@ public class SimpMessagingTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendWithCustomHeader() {
-		Map<String, Object> headers = Collections.<String, Object>singletonMap("key", "value");
+	void convertAndSendWithCustomHeader() {
+		Map<String, Object> headers = Collections.singletonMap("key", "value");
 		this.messagingTemplate.convertAndSend("/foo", "data", headers);
 
 		List<Message<byte[]>> messages = this.messageChannel.getMessages();
@@ -105,11 +104,11 @@ public class SimpMessagingTemplateTests {
 
 		assertThat(headerAccessor).isNotNull();
 		assertThat(headerAccessor.toMap().get("key")).isNull();
-		assertThat(headerAccessor.getNativeHeader("key")).isEqualTo(Arrays.asList("value"));
+		assertThat(headerAccessor.getNativeHeader("key")).containsExactly("value");
 	}
 
 	@Test
-	public void convertAndSendWithCustomHeaderNonNative() {
+	void convertAndSendWithCustomHeaderNonNative() {
 		Map<String, Object> headers = new HashMap<>();
 		headers.put("key", "value");
 		headers.put(NativeMessageHeaderAccessor.NATIVE_HEADERS, new LinkedMultiValueMap<String, String>());
@@ -128,7 +127,7 @@ public class SimpMessagingTemplateTests {
 	// SPR-11868
 
 	@Test
-	public void convertAndSendWithCustomDestinationPrefix() {
+	void convertAndSendWithCustomDestinationPrefix() {
 		this.messagingTemplate.setUserDestinationPrefix("/prefix");
 		this.messagingTemplate.convertAndSendToUser("joe", "/queue/foo", "data");
 		List<Message<byte[]>> messages = this.messageChannel.getMessages();
@@ -145,7 +144,7 @@ public class SimpMessagingTemplateTests {
 	}
 
 	@Test
-	public void convertAndSendWithMutableSimpMessageHeaders() {
+	void convertAndSendWithMutableSimpMessageHeaders() {
 		SimpMessageHeaderAccessor accessor = SimpMessageHeaderAccessor.create();
 		accessor.setHeader("key", "value");
 		accessor.setNativeHeader("fooNative", "barNative");
@@ -161,11 +160,11 @@ public class SimpMessagingTemplateTests {
 	}
 
 	@Test
-	public void processHeadersToSend() {
+	void processHeadersToSend() {
 		Map<String, Object> map = this.messagingTemplate.processHeadersToSend(null);
 
 		assertThat(map).isNotNull();
-		assertThat(MessageHeaders.class.isAssignableFrom(map.getClass())).as("Actual: " + map.getClass().toString()).isTrue();
+		assertThat(MessageHeaders.class.isAssignableFrom(map.getClass())).as("Actual: " + map.getClass()).isTrue();
 
 		SimpMessageHeaderAccessor headerAccessor =
 				MessageHeaderAccessor.getAccessor((MessageHeaders) map, SimpMessageHeaderAccessor.class);
@@ -175,7 +174,7 @@ public class SimpMessagingTemplateTests {
 	}
 
 	@Test
-	public void doSendWithMutableHeaders() {
+	void doSendWithMutableHeaders() {
 		SimpMessageHeaderAccessor accessor = SimpMessageHeaderAccessor.create();
 		accessor.setHeader("key", "value");
 		accessor.setNativeHeader("fooNative", "barNative");
@@ -192,7 +191,7 @@ public class SimpMessagingTemplateTests {
 	}
 
 	@Test
-	public void doSendWithStompHeaders() {
+	void doSendWithStompHeaders() {
 		StompHeaderAccessor accessor = StompHeaderAccessor.create(StompCommand.SUBSCRIBE);
 		accessor.setDestination("/user/queue/foo");
 		Message<?> message = MessageBuilder.createMessage(new byte[0], accessor.getMessageHeaders());
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpSessionScopeTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpSessionScopeTests.java
index 8f3416206e..eeb70d6c18 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpSessionScopeTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/SimpSessionScopeTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,7 +36,7 @@ import static org.mockito.Mockito.verify;
  * @author Rossen Stoyanchev
  * @since 4.1
  */
-public class SimpSessionScopeTests {
+class SimpSessionScopeTests {
 
 	private SimpSessionScope scope = new SimpSessionScope();
 
@@ -47,17 +47,17 @@ public class SimpSessionScopeTests {
 
 
 	@BeforeEach
-	public void setUp() {
+	void setUp() {
 		SimpAttributesContextHolder.setAttributes(this.simpAttributes);
 	}
 
 	@AfterEach
-	public void tearDown() {
+	void tearDown() {
 		SimpAttributesContextHolder.resetAttributes();
 	}
 
 	@Test
-	public void get() {
+	void get() {
 		this.simpAttributes.setAttribute("name", "value");
 		Object actual = this.scope.get("name", this.objectFactory);
 
@@ -65,7 +65,7 @@ public class SimpSessionScopeTests {
 	}
 
 	@Test
-	public void getWithObjectFactory() {
+	void getWithObjectFactory() {
 		given(this.objectFactory.getObject()).willReturn("value");
 		Object actual = this.scope.get("name", this.objectFactory);
 
@@ -74,7 +74,7 @@ public class SimpSessionScopeTests {
 	}
 
 	@Test
-	public void remove() {
+	void remove() {
 		this.simpAttributes.setAttribute("name", "value");
 
 		Object removed = this.scope.remove("name");
@@ -86,7 +86,7 @@ public class SimpSessionScopeTests {
 	}
 
 	@Test
-	public void registerDestructionCallback() {
+	void registerDestructionCallback() {
 		Runnable runnable = mock();
 		this.scope.registerDestructionCallback("name", runnable);
 
@@ -95,7 +95,7 @@ public class SimpSessionScopeTests {
 	}
 
 	@Test
-	public void getSessionId() {
+	void getSessionId() {
 		assertThat(this.scope.getConversationId()).isEqualTo("session1");
 	}
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/PrincipalMethodArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/PrincipalMethodArgumentResolverTests.java
index 7ccbb7e79a..2bb0267c78 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/PrincipalMethodArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/PrincipalMethodArgumentResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,7 +36,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Rossen Stoyanchev
  * @author Johnny Lim
  */
-public class PrincipalMethodArgumentResolverTests {
+class PrincipalMethodArgumentResolverTests {
 
 	private final PrincipalMethodArgumentResolver resolver = new PrincipalMethodArgumentResolver();
 
@@ -44,14 +44,14 @@ public class PrincipalMethodArgumentResolverTests {
 
 
 	@Test
-	public void supportsParameter() {
+	void supportsParameter() {
 		assertThat(this.resolver.supportsParameter(this.testMethod.arg(Principal.class))).isTrue();
 		assertThat(this.resolver.supportsParameter(this.testMethod.arg(Optional.class, Principal.class))).isTrue();
 	}
 
 
 	@Test
-	public void resolverArgument() {
+	void resolverArgument() {
 		Principal user = () -> "Joe";
 		Message<String> message = new GenericMessage<>("Hello, world!",
 				Collections.singletonMap(SimpMessageHeaderAccessor.USER_HEADER, user));
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/SendToMethodReturnValueHandlerTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/SendToMethodReturnValueHandlerTests.java
index 7a2861fd04..ae55bc99d4 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/SendToMethodReturnValueHandlerTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/SendToMethodReturnValueHandlerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -122,7 +122,7 @@ public class SendToMethodReturnValueHandlerTests {
 
 
 	@BeforeEach
-	public void setup() throws Exception {
+	void setup() {
 		SimpMessagingTemplate messagingTemplate = new SimpMessagingTemplate(this.messageChannel);
 		messagingTemplate.setMessageConverter(new StringMessageConverter());
 		this.handler = new SendToMethodReturnValueHandler(messagingTemplate, true);
@@ -134,7 +134,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void supportsReturnType() throws Exception {
+	void supportsReturnType() {
 		assertThat(this.handler.supportsReturnType(this.sendToReturnType)).isTrue();
 		assertThat(this.handler.supportsReturnType(this.sendToUserReturnType)).isTrue();
 		assertThat(this.handler.supportsReturnType(this.noAnnotationsReturnType)).isFalse();
@@ -150,7 +150,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToNoAnnotations() throws Exception {
+	void sendToNoAnnotations() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -162,7 +162,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendTo() throws Exception {
+	void sendTo() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -175,7 +175,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToDefaultDestination() throws Exception {
+	void sendToDefaultDestination() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -187,7 +187,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToClassDefaultNoAnnotation() throws Exception {
+	void sendToClassDefaultNoAnnotation() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -199,7 +199,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToClassDefaultEmptyAnnotation() throws Exception {
+	void sendToClassDefaultEmptyAnnotation() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -211,7 +211,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToClassDefaultOverride() throws Exception {
+	void sendToClassDefaultOverride() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -224,7 +224,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToUserClassDefaultNoAnnotation() throws Exception {
+	void sendToUserClassDefaultNoAnnotation() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -236,7 +236,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToUserClassDefaultEmptyAnnotation() throws Exception {
+	void sendToUserClassDefaultEmptyAnnotation() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -248,7 +248,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToUserClassDefaultOverride() throws Exception {
+	void sendToUserClassDefaultOverride() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -306,7 +306,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToDefaultDestinationWhenUsingDotPathSeparator() throws Exception {
+	void sendToDefaultDestinationWhenUsingDotPathSeparator() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		Message<?> inputMessage = createMessage("sess1", "sub1", "/app/", "dest.foo.bar", null);
@@ -319,7 +319,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void testHeadersToSend() throws Exception {
+	void testHeadersToSend() throws Exception {
 		Message<?> message = createMessage("sess1", "sub1", "/app", "/dest", null);
 
 		SimpMessageSendingOperations messagingTemplate = mock();
@@ -341,7 +341,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToUser() throws Exception {
+	void sendToUser() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -363,7 +363,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToAndSendToUser() throws Exception {
+	void sendToAndSendToUser() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -417,7 +417,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToUserSingleSession() throws Exception {
+	void sendToUserSingleSession() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -443,7 +443,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToUserWithUserNameProvider() throws Exception {
+	void sendToUserWithUserNameProvider() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -461,7 +461,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToUserDefaultDestination() throws Exception {
+	void sendToUserDefaultDestination() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -478,7 +478,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToUserDefaultDestinationWhenUsingDotPathSeparator() throws Exception {
+	void sendToUserDefaultDestinationWhenUsingDotPathSeparator() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		TestUser user = new TestUser();
@@ -492,7 +492,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToUserDefaultDestinationSingleSession() throws Exception {
+	void sendToUserDefaultDestinationSingleSession() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -511,7 +511,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void sendToUserSessionWithoutUserName() throws Exception {
+	void sendToUserSessionWithoutUserName() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -530,7 +530,7 @@ public class SendToMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void jsonView() throws Exception {
+	void jsonView() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandlerTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandlerTests.java
index 303aa7e82e..896aa34717 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandlerTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/SimpAnnotationMethodMessageHandlerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -99,7 +99,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 		SimpMessagingTemplate brokerTemplate = new SimpMessagingTemplate(this.channel);
 		brokerTemplate.setMessageConverter(this.converter);
 
@@ -124,7 +124,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void optionalHeaderArgumentResolutionWhenPresent() {
+	void optionalHeaderArgumentResolutionWhenPresent() {
 		Map<String, Object> headers = Collections.singletonMap("foo", "bar");
 		Message<?> message = createMessage("/pre/optionalHeaders", headers);
 		this.messageHandler.registerHandler(this.testController);
@@ -136,7 +136,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void optionalHeaderArgumentResolutionWhenNotPresent() {
+	void optionalHeaderArgumentResolutionWhenNotPresent() {
 		Message<?> message = createMessage("/pre/optionalHeaders");
 		this.messageHandler.registerHandler(this.testController);
 		this.messageHandler.handleMessage(message);
@@ -147,7 +147,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void messageMappingDestinationVariableResolution() {
+	void messageMappingDestinationVariableResolution() {
 		Message<?> message = createMessage("/pre/message/bar/value");
 		this.messageHandler.registerHandler(this.testController);
 		this.messageHandler.handleMessage(message);
@@ -158,7 +158,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void subscribeEventDestinationVariableResolution() {
+	void subscribeEventDestinationVariableResolution() {
 		Message<?> message = createMessage(SimpMessageType.SUBSCRIBE, "/pre/sub/bar/value", null);
 		this.messageHandler.registerHandler(this.testController);
 		this.messageHandler.handleMessage(message);
@@ -169,7 +169,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void simpleBinding() {
+	void simpleBinding() {
 		Message<?> message = createMessage("/pre/binding/id/12");
 		this.messageHandler.registerHandler(this.testController);
 		this.messageHandler.handleMessage(message);
@@ -180,7 +180,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void validationError() {
+	void validationError() {
 		Message<?> message = createMessage("/pre/validation/payload");
 		this.messageHandler.registerHandler(this.testController);
 		this.messageHandler.handleMessage(message);
@@ -189,7 +189,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void exceptionWithHandlerMethodArg() {
+	void exceptionWithHandlerMethodArg() {
 		Message<?> message = createMessage("/pre/illegalState");
 		this.messageHandler.registerHandler(this.testController);
 		this.messageHandler.handleMessage(message);
@@ -201,7 +201,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void exceptionAsCause() {
+	void exceptionAsCause() {
 		Message<?> message = createMessage("/pre/illegalStateCause");
 		this.messageHandler.registerHandler(this.testController);
 		this.messageHandler.handleMessage(message);
@@ -213,7 +213,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void errorAsMessageHandlingException() {
+	void errorAsMessageHandlingException() {
 		Message<?> message = createMessage("/pre/error");
 		this.messageHandler.registerHandler(this.testController);
 		this.messageHandler.handleMessage(message);
@@ -225,7 +225,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void simpScope() {
+	void simpScope() {
 		Map<String, Object> sessionAttributes = new ConcurrentHashMap<>();
 		sessionAttributes.put("name", "value");
 
@@ -241,7 +241,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void interfaceBasedController() {
+	void interfaceBasedController() {
 		InterfaceBasedController controller = new InterfaceBasedController();
 
 		Message<?> message = createMessage("/pre/binding/id/12");
@@ -254,7 +254,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void dotPathSeparator() {
+	void dotPathSeparator() {
 		DotPathSeparatorController controller = new DotPathSeparatorController();
 
 		this.messageHandler.setPathMatcher(new AntPathMatcher("."));
@@ -294,7 +294,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void listenableFutureFailure() {
+	void listenableFutureFailure() {
 		ListenableFutureController controller = new ListenableFutureController();
 		this.messageHandler.registerHandler(controller);
 		this.messageHandler.setDestinationPrefixes(Arrays.asList("/app1", "/app2/"));
@@ -327,7 +327,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void completableFutureFailure() {
+	void completableFutureFailure() {
 		CompletableFutureController controller = new CompletableFutureController();
 		this.messageHandler.registerHandler(controller);
 		this.messageHandler.setDestinationPrefixes(Arrays.asList("/app1", "/app2/"));
@@ -360,7 +360,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void monoFailure() {
+	void monoFailure() {
 		ReactiveController controller = new ReactiveController();
 		this.messageHandler.registerHandler(controller);
 		this.messageHandler.setDestinationPrefixes(Arrays.asList("/app1", "/app2/"));
@@ -373,7 +373,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void fluxNotHandled() {
+	void fluxNotHandled() {
 		ReactiveController controller = new ReactiveController();
 		this.messageHandler.registerHandler(controller);
 		this.messageHandler.setDestinationPrefixes(Arrays.asList("/app1", "/app2/"));
@@ -388,7 +388,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 	}
 
 	@Test
-	public void placeholder() {
+	void placeholder() {
 		Message<?> message = createMessage("/pre/myValue");
 		this.messageHandler.setEmbeddedValueResolver(value -> ("/${myProperty}".equals(value) ? "/myValue" : value));
 		this.messageHandler.registerHandler(this.testController);
@@ -453,7 +453,7 @@ public class SimpAnnotationMethodMessageHandlerTests {
 		public void optionalHeaders(@Header(name="foo", required=false) String foo1, @Header("foo") Optional<String> foo2) {
 			this.method = "optionalHeaders";
 			this.arguments.put("foo1", foo1);
-			this.arguments.put("foo2", (foo2.isPresent() ? foo2.get() : null));
+			this.arguments.put("foo2", (foo2.orElse(null)));
 		}
 
 		@MessageMapping("/message/{foo}/{name}")
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/SubscriptionMethodReturnValueHandlerTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/SubscriptionMethodReturnValueHandlerTests.java
index 9b4bb8abf0..0c412d4c61 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/SubscriptionMethodReturnValueHandlerTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/SubscriptionMethodReturnValueHandlerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -86,7 +86,7 @@ public class SubscriptionMethodReturnValueHandlerTests {
 
 
 	@BeforeEach
-	public void setup() throws Exception {
+	void setup() throws Exception {
 		SimpMessagingTemplate messagingTemplate = new SimpMessagingTemplate(this.messageChannel);
 		messagingTemplate.setMessageConverter(new StringMessageConverter());
 		this.handler = new SubscriptionMethodReturnValueHandler(messagingTemplate);
@@ -110,14 +110,14 @@ public class SubscriptionMethodReturnValueHandlerTests {
 
 
 	@Test
-	public void supportsReturnType() throws Exception {
+	void supportsReturnType() {
 		assertThat(this.handler.supportsReturnType(this.subscribeEventReturnType)).isTrue();
 		assertThat(this.handler.supportsReturnType(this.subscribeEventSendToReturnType)).isFalse();
 		assertThat(this.handler.supportsReturnType(this.messageMappingReturnType)).isFalse();
 	}
 
 	@Test
-	public void testMessageSentToChannel() throws Exception {
+	void testMessageSentToChannel() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
@@ -169,7 +169,7 @@ public class SubscriptionMethodReturnValueHandlerTests {
 	}
 
 	@Test
-	public void testJsonView() throws Exception {
+	void testJsonView() throws Exception {
 		given(this.messageChannel.send(any(Message.class))).willReturn(true);
 
 		String sessionId = "sess1";
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/BrokerMessageHandlerTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/BrokerMessageHandlerTests.java
index 2b2fdaac78..e0bbf0440a 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/BrokerMessageHandlerTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/BrokerMessageHandlerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,20 +39,20 @@ import static org.mockito.Mockito.mock;
  *
  * @author Rossen Stoyanchev
  */
-public class BrokerMessageHandlerTests {
+class BrokerMessageHandlerTests {
 
 	private final TestBrokerMessageHandler handler = new TestBrokerMessageHandler();
 
 
 	@Test
-	public void startShouldUpdateIsRunning() {
+	void startShouldUpdateIsRunning() {
 		assertThat(this.handler.isRunning()).isFalse();
 		this.handler.start();
 		assertThat(this.handler.isRunning()).isTrue();
 	}
 
 	@Test
-	public void stopShouldUpdateIsRunning() {
+	void stopShouldUpdateIsRunning() {
 		this.handler.start();
 		assertThat(this.handler.isRunning()).isTrue();
 
@@ -61,20 +61,20 @@ public class BrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void startAndStopShouldNotPublishBrokerAvailabilityEvents() {
+	void startAndStopShouldNotPublishBrokerAvailabilityEvents() {
 		this.handler.start();
 		this.handler.stop();
 		assertThat(this.handler.availabilityEvents).isEqualTo(Collections.emptyList());
 	}
 
 	@Test
-	public void handleMessageWhenBrokerNotRunning() {
+	void handleMessageWhenBrokerNotRunning() {
 		this.handler.handleMessage(new GenericMessage<Object>("payload"));
 		assertThat(this.handler.messages).isEqualTo(Collections.emptyList());
 	}
 
 	@Test
-	public void publishBrokerAvailableEvent() {
+	void publishBrokerAvailableEvent() {
 		assertThat(this.handler.isBrokerAvailable()).isFalse();
 		assertThat(this.handler.availabilityEvents).isEqualTo(Collections.emptyList());
 
@@ -85,7 +85,7 @@ public class BrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void publishBrokerAvailableEventWhenAlreadyAvailable() {
+	void publishBrokerAvailableEventWhenAlreadyAvailable() {
 		this.handler.publishBrokerAvailableEvent();
 		this.handler.publishBrokerAvailableEvent();
 
@@ -93,7 +93,7 @@ public class BrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void publishBrokerUnavailableEvent() {
+	void publishBrokerUnavailableEvent() {
 		this.handler.publishBrokerAvailableEvent();
 		assertThat(this.handler.isBrokerAvailable()).isTrue();
 
@@ -104,7 +104,7 @@ public class BrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void publishBrokerUnavailableEventWhenAlreadyUnavailable() {
+	void publishBrokerUnavailableEventWhenAlreadyUnavailable() {
 		this.handler.publishBrokerAvailableEvent();
 		this.handler.publishBrokerUnavailableEvent();
 		this.handler.publishBrokerUnavailableEvent();
@@ -113,7 +113,7 @@ public class BrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void checkDestination() {
+	void checkDestination() {
 		TestBrokerMessageHandler theHandler = new TestBrokerMessageHandler("/topic");
 		theHandler.start();
 
@@ -136,7 +136,7 @@ public class BrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void checkDestinationWithoutConfiguredPrefixes() {
+	void checkDestinationWithoutConfiguredPrefixes() {
 		this.handler.setUserDestinationPredicate(destination -> destination.startsWith("/user/"));
 		this.handler.start();
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/DefaultSubscriptionRegistryTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/DefaultSubscriptionRegistryTests.java
index 9416b2d94e..16914e3aaa 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/DefaultSubscriptionRegistryTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/DefaultSubscriptionRegistryTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -420,7 +420,7 @@ class DefaultSubscriptionRegistryTests {
 	}
 
 	@Test  // SPR-12665
-	void findSubscriptionsReturnsMapSafeToIterate() throws Exception {
+	void findSubscriptionsReturnsMapSafeToIterate() {
 		this.registry.registerSubscription(subscribeMessage("sess1", "1", "/foo"));
 		this.registry.registerSubscription(subscribeMessage("sess2", "1", "/foo"));
 
@@ -437,7 +437,7 @@ class DefaultSubscriptionRegistryTests {
 	}
 
 	@Test  // SPR-13185
-	void findSubscriptionsReturnsMapSafeToIterateIncludingValues() throws Exception {
+	void findSubscriptionsReturnsMapSafeToIterateIncludingValues() {
 		this.registry.registerSubscription(subscribeMessage("sess1", "1", "/foo"));
 		this.registry.registerSubscription(subscribeMessage("sess1", "2", "/foo"));
 
@@ -454,7 +454,7 @@ class DefaultSubscriptionRegistryTests {
 	}
 
 	@Test // SPR-13555
-	void cacheLimitExceeded() throws Exception {
+	void cacheLimitExceeded() {
 		this.registry.setCacheLimit(1);
 		this.registry.registerSubscription(subscribeMessage("sess1", "1", "/foo"));
 		this.registry.registerSubscription(subscribeMessage("sess1", "2", "/bar"));
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/OrderedMessageChannelDecoratorTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/OrderedMessageChannelDecoratorTests.java
index 38449318ac..4aabe617c0 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/OrderedMessageChannelDecoratorTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/OrderedMessageChannelDecoratorTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,7 +43,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Rossen Stoyanchev
  * @see org.springframework.web.socket.messaging.OrderedMessageSendingIntegrationTests
  */
-public class OrderedMessageChannelDecoratorTests {
+class OrderedMessageChannelDecoratorTests {
 
 	private static final Log logger = LogFactory.getLog(OrderedMessageChannelDecoratorTests.class);
 
@@ -52,7 +52,7 @@ public class OrderedMessageChannelDecoratorTests {
 
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 		this.executor = new ThreadPoolTaskExecutor();
 		this.executor.setCorePoolSize(Runtime.getRuntime().availableProcessors() * 2);
 		this.executor.setAllowCoreThreadTimeOut(true);
@@ -60,13 +60,13 @@ public class OrderedMessageChannelDecoratorTests {
 	}
 
 	@AfterEach
-	public void tearDown() {
+	void tearDown() {
 		this.executor.shutdown();
 	}
 
 
 	@Test
-	public void test() throws InterruptedException {
+	void test() throws InterruptedException {
 
 		int start = 1;
 		int end = 1000;
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/SimpleBrokerMessageHandlerTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/SimpleBrokerMessageHandlerTests.java
index 4764347629..1c20b4978b 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/SimpleBrokerMessageHandlerTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/broker/SimpleBrokerMessageHandlerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -82,14 +82,14 @@ public class SimpleBrokerMessageHandlerTests {
 
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 		this.messageHandler = new SimpleBrokerMessageHandler(
 				this.clientInChannel, this.clientOutChannel, this.brokerChannel, Collections.emptyList());
 	}
 
 
 	@Test
-	public void subscribePublish() {
+	void subscribePublish() {
 		startSession("sess1");
 		startSession("sess2");
 
@@ -114,7 +114,7 @@ public class SimpleBrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void subscribeDisconnectPublish() {
+	void subscribeDisconnectPublish() {
 		String sess1 = "sess1";
 		String sess2 = "sess2";
 
@@ -152,7 +152,7 @@ public class SimpleBrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void connect() {
+	void connect() {
 		String id = "sess1";
 
 		Message<String> connectMessage = startSession(id);
@@ -166,7 +166,7 @@ public class SimpleBrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void heartbeatValueWithAndWithoutTaskScheduler() {
+	void heartbeatValueWithAndWithoutTaskScheduler() {
 		assertThat(this.messageHandler.getHeartbeatValue()).isNull();
 		this.messageHandler.setTaskScheduler(this.taskScheduler);
 
@@ -175,7 +175,7 @@ public class SimpleBrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void startWithHeartbeatValueWithoutTaskScheduler() {
+	void startWithHeartbeatValueWithoutTaskScheduler() {
 		this.messageHandler.setHeartbeatValue(new long[] {10000, 10000});
 		assertThatIllegalArgumentException().isThrownBy(
 				this.messageHandler::start);
@@ -201,7 +201,7 @@ public class SimpleBrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void startWithOneZeroHeartbeatValue() {
+	void startWithOneZeroHeartbeatValue() {
 		this.messageHandler.setTaskScheduler(this.taskScheduler);
 		this.messageHandler.setHeartbeatValue(new long[] {0, 10000});
 		this.messageHandler.start();
@@ -210,7 +210,7 @@ public class SimpleBrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void readInactivity() throws Exception {
+	void readInactivity() throws Exception {
 		this.messageHandler.setHeartbeatValue(new long[] {0, 1});
 		this.messageHandler.setTaskScheduler(this.taskScheduler);
 		this.messageHandler.start();
@@ -241,7 +241,7 @@ public class SimpleBrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void writeInactivity() throws Exception {
+	void writeInactivity() throws Exception {
 		this.messageHandler.setHeartbeatValue(new long[] {1, 0});
 		this.messageHandler.setTaskScheduler(this.taskScheduler);
 		this.messageHandler.start();
@@ -272,7 +272,7 @@ public class SimpleBrokerMessageHandlerTests {
 	}
 
 	@Test
-	public void readWriteIntervalCalculation() throws Exception {
+	void readWriteIntervalCalculation() throws Exception {
 		this.messageHandler.setHeartbeatValue(new long[] {1, 1});
 		this.messageHandler.setTaskScheduler(this.taskScheduler);
 		this.messageHandler.start();
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/config/MessageBrokerConfigurationTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/config/MessageBrokerConfigurationTests.java
index 2039face36..95df76e0b7 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/config/MessageBrokerConfigurationTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/config/MessageBrokerConfigurationTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -92,10 +92,10 @@ import static org.mockito.Mockito.mock;
  * @author Brian Clozel
  * @author Sebastien Deleuze
  */
-public class MessageBrokerConfigurationTests {
+class MessageBrokerConfigurationTests {
 
 	@Test
-	public void clientInboundChannel() {
+	void clientInboundChannel() {
 		ApplicationContext context = loadConfig(SimpleBrokerConfig.class);
 
 		TestChannel channel = context.getBean("clientInboundChannel", TestChannel.class);
@@ -108,7 +108,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void clientInboundChannelWithBrokerRelay() {
+	void clientInboundChannelWithBrokerRelay() {
 		ApplicationContext context = loadConfig(BrokerRelayConfig.class);
 
 		TestChannel channel = context.getBean("clientInboundChannel", TestChannel.class);
@@ -121,7 +121,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void clientInboundChannelCustomized() {
+	void clientInboundChannelCustomized() {
 		ApplicationContext context = loadConfig(CustomConfig.class);
 
 		AbstractSubscribableChannel channel = context.getBean(
@@ -136,7 +136,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void clientOutboundChannelUsedByAnnotatedMethod() {
+	void clientOutboundChannelUsedByAnnotatedMethod() {
 		ApplicationContext context = loadConfig(SimpleBrokerConfig.class);
 
 		TestChannel channel = context.getBean("clientOutboundChannel", TestChannel.class);
@@ -161,7 +161,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void clientOutboundChannelUsedBySimpleBroker() {
+	void clientOutboundChannelUsedBySimpleBroker() {
 		ApplicationContext context = loadConfig(SimpleBrokerConfig.class);
 
 		TestChannel outboundChannel = context.getBean("clientOutboundChannel", TestChannel.class);
@@ -194,7 +194,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void clientOutboundChannelCustomized() {
+	void clientOutboundChannelCustomized() {
 		ApplicationContext context = loadConfig(CustomConfig.class);
 
 		AbstractSubscribableChannel channel = context.getBean(
@@ -215,7 +215,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void brokerChannel() {
+	void brokerChannel() {
 		ApplicationContext context = loadConfig(SimpleBrokerConfig.class);
 
 		TestChannel channel = context.getBean("brokerChannel", TestChannel.class);
@@ -229,7 +229,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void brokerChannelWithBrokerRelay() {
+	void brokerChannelWithBrokerRelay() {
 		ApplicationContext context = loadConfig(BrokerRelayConfig.class);
 
 		TestChannel channel = context.getBean("brokerChannel", TestChannel.class);
@@ -241,7 +241,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void brokerChannelUsedByAnnotatedMethod() {
+	void brokerChannelUsedByAnnotatedMethod() {
 		ApplicationContext context = loadConfig(SimpleBrokerConfig.class);
 
 		TestChannel channel = context.getBean("brokerChannel", TestChannel.class);
@@ -265,7 +265,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void brokerChannelCustomized() {
+	void brokerChannelCustomized() {
 		ApplicationContext context = loadConfig(CustomConfig.class);
 
 		AbstractSubscribableChannel channel = context.getBean(
@@ -282,7 +282,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void configureMessageConvertersDefault() {
+	void configureMessageConvertersDefault() {
 		AbstractMessageBrokerConfiguration config = new BaseTestMessageBrokerConfig();
 		CompositeMessageConverter compositeConverter = config.brokerMessageConverter();
 
@@ -298,7 +298,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void threadPoolSizeDefault() {
+	void threadPoolSizeDefault() {
 		ApplicationContext context = loadConfig(DefaultConfig.class);
 
 		String name = "clientInboundChannelExecutor";
@@ -317,7 +317,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void configureMessageConvertersCustom() {
+	void configureMessageConvertersCustom() {
 		final MessageConverter testConverter = mock();
 		AbstractMessageBrokerConfiguration config = new BaseTestMessageBrokerConfig() {
 			@Override
@@ -334,7 +334,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void configureMessageConvertersCustomAndDefault() {
+	void configureMessageConvertersCustomAndDefault() {
 		final MessageConverter testConverter = mock();
 
 		AbstractMessageBrokerConfiguration config = new BaseTestMessageBrokerConfig() {
@@ -356,7 +356,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void customArgumentAndReturnValueTypes() {
+	void customArgumentAndReturnValueTypes() {
 		ApplicationContext context = loadConfig(CustomConfig.class);
 
 		SimpAnnotationMethodMessageHandler handler =
@@ -372,7 +372,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void simpValidatorDefault() {
+	void simpValidatorDefault() {
 		AbstractMessageBrokerConfiguration config = new BaseTestMessageBrokerConfig() {};
 		config.setApplicationContext(new StaticApplicationContext());
 
@@ -381,7 +381,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void simpValidatorCustom() {
+	void simpValidatorCustom() {
 		final Validator validator = mock();
 		AbstractMessageBrokerConfiguration config = new BaseTestMessageBrokerConfig() {
 			@Override
@@ -394,7 +394,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void simpValidatorMvc() {
+	void simpValidatorMvc() {
 		StaticApplicationContext appCxt = new StaticApplicationContext();
 		appCxt.registerSingleton("mvcValidator", TestValidator.class);
 		AbstractMessageBrokerConfiguration config = new BaseTestMessageBrokerConfig() {};
@@ -405,7 +405,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void simpValidatorInjected() {
+	void simpValidatorInjected() {
 		ApplicationContext context = loadConfig(SimpleBrokerConfig.class);
 
 		SimpAnnotationMethodMessageHandler messageHandler =
@@ -415,7 +415,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void customPathMatcher() {
+	void customPathMatcher() {
 		ApplicationContext context = loadConfig(CustomConfig.class);
 
 		SimpleBrokerMessageHandler broker = context.getBean(SimpleBrokerMessageHandler.class);
@@ -433,7 +433,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void customCacheLimit() {
+	void customCacheLimit() {
 		ApplicationContext context = loadConfig(CustomConfig.class);
 
 		SimpleBrokerMessageHandler broker = context.getBean(SimpleBrokerMessageHandler.class);
@@ -442,7 +442,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void customUserRegistryOrder() {
+	void customUserRegistryOrder() {
 		ApplicationContext context = loadConfig(CustomConfig.class);
 
 		SimpUserRegistry registry = context.getBean(SimpUserRegistry.class);
@@ -451,7 +451,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void userBroadcasts() {
+	void userBroadcasts() {
 		ApplicationContext context = loadConfig(BrokerRelayConfig.class);
 
 		SimpUserRegistry userRegistry = context.getBean(SimpUserRegistry.class);
@@ -471,7 +471,7 @@ public class MessageBrokerConfigurationTests {
 	}
 
 	@Test
-	public void userBroadcastsDisabledWithSimpleBroker() {
+	void userBroadcastsDisabledWithSimpleBroker() {
 		ApplicationContext context = loadConfig(SimpleBrokerConfig.class);
 
 		SimpUserRegistry registry = context.getBean(SimpUserRegistry.class);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/config/StompBrokerRelayRegistrationTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/config/StompBrokerRelayRegistrationTests.java
index 462c43e794..ac4c5e4e70 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/config/StompBrokerRelayRegistrationTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/config/StompBrokerRelayRegistrationTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -32,10 +32,10 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Rossen Stoyanchev
  */
-public class StompBrokerRelayRegistrationTests {
+class StompBrokerRelayRegistrationTests {
 
 	@Test
-	public void test() {
+	void test() {
 
 		SubscribableChannel inChannel = new StubMessageChannel();
 		MessageChannel outChannel = new StubMessageChannel();
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/AbstractStompBrokerRelayIntegrationTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/AbstractStompBrokerRelayIntegrationTests.java
index fe40e62fdd..ed1fe62fa9 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/AbstractStompBrokerRelayIntegrationTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/AbstractStompBrokerRelayIntegrationTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -77,7 +77,7 @@ public abstract class AbstractStompBrokerRelayIntegrationTests {
 
 
 	@BeforeEach
-	public void setup(TestInfo testInfo) throws Exception {
+	void setup(TestInfo testInfo) throws Exception {
 		logger.debug("Setting up before '" + testInfo.getTestMethod().get().getName() + "'");
 
 		this.responseChannel = new ExecutorSubscribableChannel();
@@ -130,7 +130,7 @@ public abstract class AbstractStompBrokerRelayIntegrationTests {
 	protected abstract TcpOperations<byte[]> initTcpClient(int port);
 
 	@AfterEach
-	public void stop() throws Exception {
+	void stop() throws Exception {
 		try {
 			logger.debug("STOMP broker relay stats: " + this.relay.getStatsInfo());
 			this.relay.stop();
@@ -155,7 +155,7 @@ public abstract class AbstractStompBrokerRelayIntegrationTests {
 
 
 	@Test
-	public void publishSubscribe() throws Exception {
+	void publishSubscribe() throws Exception {
 		logger.debug("Starting test publishSubscribe()");
 
 		String sess1 = "sess1";
@@ -179,7 +179,7 @@ public abstract class AbstractStompBrokerRelayIntegrationTests {
 	}
 
 	@Test
-	public void messageDeliveryExceptionIfSystemSessionForwardFails() throws Exception {
+	void messageDeliveryExceptionIfSystemSessionForwardFails() throws Exception {
 		logger.debug("Starting test messageDeliveryExceptionIfSystemSessionForwardFails()");
 
 		stopActiveMqBrokerAndAwait();
@@ -191,7 +191,7 @@ public abstract class AbstractStompBrokerRelayIntegrationTests {
 	}
 
 	@Test
-	public void brokerBecomingUnavailableTriggersErrorFrame() throws Exception {
+	void brokerBecomingUnavailableTriggersErrorFrame() throws Exception {
 		logger.debug("Starting test brokerBecomingUnavailableTriggersErrorFrame()");
 
 		String sess1 = "sess1";
@@ -206,7 +206,7 @@ public abstract class AbstractStompBrokerRelayIntegrationTests {
 	}
 
 	@Test
-	public void brokerAvailabilityEventWhenStopped() throws Exception {
+	void brokerAvailabilityEventWhenStopped() throws Exception {
 		logger.debug("Starting test brokerAvailabilityEventWhenStopped()");
 
 		stopActiveMqBrokerAndAwait();
@@ -214,7 +214,7 @@ public abstract class AbstractStompBrokerRelayIntegrationTests {
 	}
 
 	@Test
-	public void relayReconnectsIfBrokerComesBackUp() throws Exception {
+	void relayReconnectsIfBrokerComesBackUp() throws Exception {
 		logger.debug("Starting test relayReconnectsIfBrokerComesBackUp()");
 
 		String sess1 = "sess1";
@@ -240,7 +240,7 @@ public abstract class AbstractStompBrokerRelayIntegrationTests {
 	}
 
 	@Test
-	public void disconnectWithReceipt() throws Exception {
+	void disconnectWithReceipt() throws Exception {
 		logger.debug("Starting test disconnectWithReceipt()");
 
 		MessageExchange connect = MessageExchangeBuilder.connect("sess1").build();
@@ -443,7 +443,7 @@ public abstract class AbstractStompBrokerRelayIntegrationTests {
 		}
 
 		public MessageExchange build() {
-			return new MessageExchange(this.message, this.expected.toArray(new MessageMatcher[this.expected.size()]));
+			return new MessageExchange(this.message, this.expected.toArray(new MessageMatcher[0]));
 		}
 	}
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/BufferingStompDecoderTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/BufferingStompDecoderTests.java
index 251f904dd2..9aefe41b92 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/BufferingStompDecoderTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/BufferingStompDecoderTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,13 +34,13 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
  * @author Rossen Stoyanchev
  * @since 4.0.3
  */
-public class BufferingStompDecoderTests {
+class BufferingStompDecoderTests {
 
-	private final StompDecoder STOMP_DECODER = new StompDecoder();
+	private static final StompDecoder STOMP_DECODER = new StompDecoder();
 
 
 	@Test
-	public void basic() throws InterruptedException {
+	void basic() {
 		BufferingStompDecoder stompDecoder = new BufferingStompDecoder(STOMP_DECODER, 128);
 		String chunk = "SEND\na:alpha\n\nMessage body\0";
 
@@ -53,7 +53,7 @@ public class BufferingStompDecoderTests {
 	}
 
 	@Test
-	public void oneMessageInTwoChunks() throws InterruptedException {
+	void oneMessageInTwoChunks() {
 		BufferingStompDecoder stompDecoder = new BufferingStompDecoder(STOMP_DECODER, 128);
 		String chunk1 = "SEND\na:alpha\n\nMessage";
 		String chunk2 = " body\0";
@@ -70,7 +70,7 @@ public class BufferingStompDecoderTests {
 	}
 
 	@Test
-	public void twoMessagesInOneChunk() throws InterruptedException {
+	void twoMessagesInOneChunk() {
 		BufferingStompDecoder stompDecoder = new BufferingStompDecoder(STOMP_DECODER, 128);
 		String chunk = """
 				SEND
@@ -91,7 +91,7 @@ public class BufferingStompDecoderTests {
 	}
 
 	@Test
-	public void oneFullAndOneSplitMessageContentLength() throws InterruptedException {
+	void oneFullAndOneSplitMessageContentLength() {
 		BufferingStompDecoder stompDecoder = new BufferingStompDecoder(STOMP_DECODER, 128);
 		int contentLength = "Payload2a-Payload2b".getBytes().length;
 		String chunk1 = "SEND\na:alpha\n\nPayload1\0SEND\ncontent-length:" + contentLength + "\n";
@@ -120,7 +120,7 @@ public class BufferingStompDecoderTests {
 	}
 
 	@Test
-	public void oneFullAndOneSplitMessageNoContentLength() throws InterruptedException {
+	void oneFullAndOneSplitMessageNoContentLength() {
 		BufferingStompDecoder stompDecoder = new BufferingStompDecoder(STOMP_DECODER, 128);
 		String chunk1 = "SEND\na:alpha\n\nPayload1\0SEND\na:alpha\n";
 		List<Message<byte[]>> messages = stompDecoder.decode(toByteBuffer(chunk1));
@@ -148,7 +148,7 @@ public class BufferingStompDecoderTests {
 	}
 
 	@Test
-	public void oneFullAndOneSplitWithContentLengthExceedingBufferSize() throws InterruptedException {
+	void oneFullAndOneSplitWithContentLengthExceedingBufferSize() {
 		BufferingStompDecoder stompDecoder = new BufferingStompDecoder(STOMP_DECODER, 128);
 		String chunk1 = "SEND\na:alpha\n\nPayload1\0SEND\ncontent-length:129\n";
 		List<Message<byte[]>> messages = stompDecoder.decode(toByteBuffer(chunk1));
@@ -165,7 +165,7 @@ public class BufferingStompDecoderTests {
 	}
 
 	@Test
-	public void bufferSizeLimit() {
+	void bufferSizeLimit() {
 		BufferingStompDecoder stompDecoder = new BufferingStompDecoder(STOMP_DECODER, 10);
 		String payload = "SEND\na:alpha\n\nMessage body";
 		assertThatExceptionOfType(StompConversionException.class).isThrownBy(() ->
@@ -173,7 +173,7 @@ public class BufferingStompDecoderTests {
 	}
 
 	@Test
-	public void incompleteCommand() {
+	void incompleteCommand() {
 		BufferingStompDecoder stompDecoder = new BufferingStompDecoder(STOMP_DECODER, 128);
 		String chunk = "MESSAG";
 
@@ -184,7 +184,7 @@ public class BufferingStompDecoderTests {
 	// SPR-13416
 
 	@Test
-	public void incompleteHeaderWithPartialEscapeSequence() throws Exception {
+	void incompleteHeaderWithPartialEscapeSequence() {
 		BufferingStompDecoder stompDecoder = new BufferingStompDecoder(STOMP_DECODER, 128);
 		String chunk = "SEND\na:long\\";
 
@@ -193,7 +193,7 @@ public class BufferingStompDecoderTests {
 	}
 
 	@Test
-	public void invalidEscapeSequence() {
+	void invalidEscapeSequence() {
 		BufferingStompDecoder stompDecoder = new BufferingStompDecoder(STOMP_DECODER, 128);
 		String payload = "SEND\na:alpha\\x\\n\nMessage body\0";
 		assertThatExceptionOfType(StompConversionException.class).isThrownBy(() ->
@@ -201,7 +201,7 @@ public class BufferingStompDecoderTests {
 	}
 
 	@Test
-	public void invalidEscapeSequenceWithSingleSlashAtEndOfHeaderValue() {
+	void invalidEscapeSequenceWithSingleSlashAtEndOfHeaderValue() {
 		BufferingStompDecoder stompDecoder = new BufferingStompDecoder(STOMP_DECODER, 128);
 		String payload = "SEND\na:alpha\\\n\nMessage body\0";
 		assertThatExceptionOfType(StompConversionException.class).isThrownBy(() ->
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/DefaultStompSessionTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/DefaultStompSessionTests.java
index 840917f125..d0947cbe3b 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/DefaultStompSessionTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/DefaultStompSessionTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -83,7 +83,7 @@ public class DefaultStompSessionTests {
 
 
 	@BeforeEach
-	public void setUp() {
+	void setUp() {
 		this.connectHeaders = new StompHeaders();
 		this.session = new DefaultStompSession(this.sessionHandler, this.connectHeaders);
 		this.session.setMessageConverter(
@@ -97,7 +97,7 @@ public class DefaultStompSessionTests {
 
 
 	@Test
-	public void afterConnected() {
+	void afterConnected() {
 		assertThat(this.session.isConnected()).isFalse();
 		this.connectHeaders.setHost("my-host");
 		this.connectHeaders.setHeartbeat(new long[] {11, 12});
@@ -127,7 +127,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void afterConnectFailure() {
+	void afterConnectFailure() {
 		IllegalStateException exception = new IllegalStateException("simulated exception");
 		this.session.afterConnectFailure(exception);
 		verify(this.sessionHandler).handleTransportError(this.session, exception);
@@ -135,7 +135,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void handleConnectedFrame() {
+	void handleConnectedFrame() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -153,7 +153,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void heartbeatValues() {
+	void heartbeatValues() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -175,7 +175,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void heartbeatNotSupportedByServer() {
+	void heartbeatNotSupportedByServer() {
 		this.session.afterConnected(this.connection);
 		verify(this.connection).sendAsync(any());
 
@@ -191,7 +191,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void heartbeatTasks() {
+	void heartbeatTasks() {
 		this.session.afterConnected(this.connection);
 		verify(this.connection).sendAsync(any());
 
@@ -226,7 +226,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void handleErrorFrame() {
+	void handleErrorFrame() {
 		StompHeaderAccessor accessor = StompHeaderAccessor.create(StompCommand.ERROR);
 		accessor.setContentType(new MimeType("text", "plain", StandardCharsets.UTF_8));
 		accessor.addNativeHeader("foo", "bar");
@@ -245,7 +245,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void handleErrorFrameWithEmptyPayload() {
+	void handleErrorFrameWithEmptyPayload() {
 		StompHeaderAccessor accessor = StompHeaderAccessor.create(StompCommand.ERROR);
 		accessor.addNativeHeader("foo", "bar");
 		accessor.setLeaveMutable(true);
@@ -257,7 +257,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void handleErrorFrameWithConversionException() {
+	void handleErrorFrameWithConversionException() {
 		StompHeaderAccessor accessor = StompHeaderAccessor.create(StompCommand.ERROR);
 		accessor.setContentType(MimeTypeUtils.APPLICATION_JSON);
 		accessor.addNativeHeader("foo", "bar");
@@ -276,7 +276,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void handleMessageFrame() {
+	void handleMessageFrame() {
 		this.session.afterConnected(this.connection);
 
 		StompFrameHandler frameHandler = mock();
@@ -303,7 +303,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void handleMessageFrameWithConversionException() {
+	void handleMessageFrameWithConversionException() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -333,7 +333,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void handleFailure() {
+	void handleFailure() {
 		IllegalStateException exception = new IllegalStateException("simulated exception");
 		this.session.handleFailure(exception);
 
@@ -342,7 +342,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void afterConnectionClosed() {
+	void afterConnectionClosed() {
 		this.session.afterConnectionClosed();
 
 		verify(this.sessionHandler).handleTransportError(same(this.session), any(ConnectionLostException.class));
@@ -350,7 +350,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void send() {
+	void send() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -373,7 +373,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void sendWithReceipt() {
+	void sendWithReceipt() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -416,7 +416,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void sendWithConversionException() {
+	void sendWithConversionException() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -430,7 +430,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void sendWithExecutionException() {
+	void sendWithExecutionException() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -444,7 +444,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void subscribe() {
+	void subscribe() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -463,7 +463,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void subscribeWithHeaders() {
+	void subscribeWithHeaders() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -489,7 +489,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void unsubscribe() {
+	void unsubscribe() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -536,7 +536,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void ack() {
+	void ack() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -553,7 +553,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void nack() {
+	void nack() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -570,7 +570,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void receiptReceived() {
+	void receiptReceived() {
 		this.session.afterConnected(this.connection);
 		this.session.setTaskScheduler(mock());
 
@@ -597,12 +597,11 @@ public class DefaultStompSessionTests {
 		assertThat(received.get()).isNotNull();
 		assertThat(received.get()).isTrue();
 		assertThat(receivedHeaders.get()).isNotNull();
-		assertThat(receivedHeaders.get().get("foo")).hasSize(1);
-		assertThat(receivedHeaders.get().get("foo")).element(0).isEqualTo("bar");
+		assertThat(receivedHeaders.get().get("foo")).containsExactly("bar");
 	}
 
 	@Test
-	public void receiptReceivedBeforeTaskAdded() {
+	void receiptReceivedBeforeTaskAdded() {
 		this.session.afterConnected(this.connection);
 		this.session.setTaskScheduler(mock());
 
@@ -628,8 +627,7 @@ public class DefaultStompSessionTests {
 		assertThat(received.get()).isNotNull();
 		assertThat(received.get()).isTrue();
 		assertThat(receivedHeaders.get()).isNotNull();
-		assertThat(receivedHeaders.get().get("foo")).hasSize(1);
-		assertThat(receivedHeaders.get().get("foo")).element(0).isEqualTo("bar");
+		assertThat(receivedHeaders.get().get("foo")).containsExactly("bar");
 	}
 
 	@Test
@@ -665,7 +663,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void disconnect() {
+	void disconnect() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -675,7 +673,7 @@ public class DefaultStompSessionTests {
 	}
 
 	@Test
-	public void disconnectWithHeaders() {
+	void disconnectWithHeaders() {
 		this.session.afterConnected(this.connection);
 		assertThat(this.session.isConnected()).isTrue();
 
@@ -688,8 +686,7 @@ public class DefaultStompSessionTests {
 		StompHeaderAccessor accessor = MessageHeaderAccessor.getAccessor(message, StompHeaderAccessor.class);
 		headers = StompHeaders.readOnlyStompHeaders(accessor.getNativeHeaders());
 		assertThat(headers).as(headers.toString()).hasSize(1);
-		assertThat(headers.get("foo")).hasSize(1);
-		assertThat(headers.get("foo")).element(0).isEqualTo("bar");
+		assertThat(headers.get("foo")).containsExactly("bar");
 
 		assertThat(this.session.isConnected()).isFalse();
 		verifyNoMoreInteractions(this.sessionHandler);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/ReactorNettyStompBrokerRelayIntegrationTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/ReactorNettyStompBrokerRelayIntegrationTests.java
index 2ea1bf8ee2..2b63d40a3f 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/ReactorNettyStompBrokerRelayIntegrationTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/ReactorNettyStompBrokerRelayIntegrationTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,7 +25,7 @@ import org.springframework.messaging.tcp.reactor.ReactorNettyTcpClient;
  *
  * @author Rossen Stoyanchev
  */
-public class ReactorNettyStompBrokerRelayIntegrationTests extends AbstractStompBrokerRelayIntegrationTests {
+class ReactorNettyStompBrokerRelayIntegrationTests extends AbstractStompBrokerRelayIntegrationTests {
 
 	@Override
 	protected TcpOperations<byte[]> initTcpClient(int port) {
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/ReactorNettyTcpStompClientTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/ReactorNettyTcpStompClientTests.java
index 6204f53ca5..65d54e3616 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/ReactorNettyTcpStompClientTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/ReactorNettyTcpStompClientTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,7 +49,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Rossen Stoyanchev
  * @author Sam Brannen
  */
-public class ReactorNettyTcpStompClientTests {
+class ReactorNettyTcpStompClientTests {
 
 	private static final Log logger = LogFactory.getLog(ReactorNettyTcpStompClientTests.class);
 
@@ -62,7 +62,7 @@ public class ReactorNettyTcpStompClientTests {
 
 
 	@BeforeEach
-	public void setup(TestInfo testInfo) throws Exception {
+	void setup(TestInfo testInfo) throws Exception {
 		logger.debug("Setting up before '" + testInfo.getTestMethod().get().getName() + "'");
 
 		TransportConnector stompConnector = createStompConnector();
@@ -97,7 +97,7 @@ public class ReactorNettyTcpStompClientTests {
 	}
 
 	@AfterEach
-	public void shutdown() throws Exception {
+	void shutdown() throws Exception {
 		try {
 			this.client.shutdown();
 			this.client2.shutdown();
@@ -116,12 +116,12 @@ public class ReactorNettyTcpStompClientTests {
 
 
 	@Test
-	public void publishSubscribeOnReactorNetty() throws Exception {
+	void publishSubscribeOnReactorNetty() throws Exception {
 		testPublishSubscribe(this.client);
 	}
 
 	@Test
-	public void publishSubscribeOnReactorNetty2() throws Exception {
+	void publishSubscribeOnReactorNetty2() throws Exception {
 		testPublishSubscribe(this.client2);
 	}
 
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompClientSupportTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompClientSupportTests.java
index c4cf1f118b..16fc72dcbc 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompClientSupportTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompClientSupportTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,13 +26,13 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  *
  * @author Rossen Stoyanchev
  */
-public class StompClientSupportTests {
+class StompClientSupportTests {
 
 	private final StompClientSupport stompClient = new StompClientSupport() {};
 
 
 	@Test
-	public void defaultHeartbeatValidation() throws Exception {
+	void defaultHeartbeatValidation() {
 		trySetDefaultHeartbeat(new long[] {-1, 0});
 		trySetDefaultHeartbeat(new long[] {0, -1});
 	}
@@ -43,12 +43,12 @@ public class StompClientSupportTests {
 	}
 
 	@Test
-	public void defaultHeartbeatValue() throws Exception {
+	void defaultHeartbeatValue() {
 		assertThat(this.stompClient.getDefaultHeartbeat()).isEqualTo(new long[] {10000, 10000});
 	}
 
 	@Test
-	public void isDefaultHeartbeatEnabled() throws Exception {
+	void isDefaultHeartbeatEnabled() {
 		assertThat(this.stompClient.getDefaultHeartbeat()).isEqualTo(new long[] {10000, 10000});
 		assertThat(this.stompClient.isDefaultHeartbeatEnabled()).isTrue();
 
@@ -57,7 +57,7 @@ public class StompClientSupportTests {
 	}
 
 	@Test
-	public void processConnectHeadersDefault() throws Exception {
+	void processConnectHeadersDefault() {
 		StompHeaders connectHeaders = this.stompClient.processConnectHeaders(null);
 
 		assertThat(connectHeaders).isNotNull();
@@ -65,7 +65,7 @@ public class StompClientSupportTests {
 	}
 
 	@Test
-	public void processConnectHeadersWithExplicitHeartbeat() throws Exception {
+	void processConnectHeadersWithExplicitHeartbeat() {
 
 		StompHeaders connectHeaders = new StompHeaders();
 		connectHeaders.setHeartbeat(new long[] {15000, 15000});
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompCommandTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompCommandTests.java
index 870c8240bd..2a603fb5bf 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompCommandTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompCommandTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,7 +30,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 /**
  * @author Juergen Hoeller
  */
-public class StompCommandTests {
+class StompCommandTests {
 
 	private static final Collection<StompCommand> destinationRequired =
 			Arrays.asList(StompCommand.SEND, StompCommand.SUBSCRIBE, StompCommand.MESSAGE);
@@ -59,7 +59,7 @@ public class StompCommandTests {
 
 
 	@Test
-	public void getMessageType() throws Exception {
+	void getMessageType() {
 		for (StompCommand stompCommand : StompCommand.values()) {
 			SimpMessageType simp = messageTypes.get(stompCommand);
 			if (simp == null) {
@@ -70,28 +70,28 @@ public class StompCommandTests {
 	}
 
 	@Test
-	public void requiresDestination() throws Exception {
+	void requiresDestination() {
 		for (StompCommand stompCommand : StompCommand.values()) {
 			assertThat(stompCommand.requiresDestination()).isEqualTo(destinationRequired.contains(stompCommand));
 		}
 	}
 
 	@Test
-	public void requiresSubscriptionId() throws Exception {
+	void requiresSubscriptionId() {
 		for (StompCommand stompCommand : StompCommand.values()) {
 			assertThat(stompCommand.requiresSubscriptionId()).isEqualTo(subscriptionIdRequired.contains(stompCommand));
 		}
 	}
 
 	@Test
-	public void requiresContentLength() throws Exception {
+	void requiresContentLength() {
 		for (StompCommand stompCommand : StompCommand.values()) {
 			assertThat(stompCommand.requiresContentLength()).isEqualTo(contentLengthRequired.contains(stompCommand));
 		}
 	}
 
 	@Test
-	public void isBodyAllowed() throws Exception {
+	void isBodyAllowed() {
 		for (StompCommand stompCommand : StompCommand.values()) {
 			assertThat(stompCommand.isBodyAllowed()).isEqualTo(bodyAllowed.contains(stompCommand));
 		}
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompDecoderTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompDecoderTests.java
index 0372d4e5e2..195e4fb1c0 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompDecoderTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompDecoderTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,13 +34,13 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
  * @author Andy Wilkinson
  * @author Stephane Maldini
  */
-public class StompDecoderTests {
+class StompDecoderTests {
 
 	private final StompDecoder decoder = new StompDecoder();
 
 
 	@Test
-	public void decodeFrameWithCrLfEols() {
+	void decodeFrameWithCrLfEols() {
 		Message<byte[]> frame = decode("DISCONNECT\r\n\r\n\0");
 		StompHeaderAccessor headers = StompHeaderAccessor.wrap(frame);
 
@@ -50,7 +50,7 @@ public class StompDecoderTests {
 	}
 
 	@Test
-	public void decodeFrameWithNoHeadersAndNoBody() {
+	void decodeFrameWithNoHeadersAndNoBody() {
 		Message<byte[]> frame = decode("DISCONNECT\n\n\0");
 		StompHeaderAccessor headers = StompHeaderAccessor.wrap(frame);
 
@@ -60,7 +60,7 @@ public class StompDecoderTests {
 	}
 
 	@Test
-	public void decodeFrameWithNoBody() {
+	void decodeFrameWithNoBody() {
 		String accept = "accept-version:1.1\n";
 		String host = "host:github.org\n";
 
@@ -77,7 +77,7 @@ public class StompDecoderTests {
 	}
 
 	@Test
-	public void decodeFrame() {
+	void decodeFrame() {
 		Message<byte[]> frame = decode("SEND\ndestination:test\n\nThe body of the message\0");
 		StompHeaderAccessor headers = StompHeaderAccessor.wrap(frame);
 
@@ -91,7 +91,7 @@ public class StompDecoderTests {
 	}
 
 	@Test
-	public void decodeFrameWithContentLength() {
+	void decodeFrameWithContentLength() {
 		Message<byte[]> message = decode("SEND\ncontent-length:23\n\nThe body of the message\0");
 		StompHeaderAccessor headers = StompHeaderAccessor.wrap(message);
 
@@ -107,7 +107,7 @@ public class StompDecoderTests {
 	// SPR-11528
 
 	@Test
-	public void decodeFrameWithInvalidContentLength() {
+	void decodeFrameWithInvalidContentLength() {
 		Message<byte[]> message = decode("SEND\ncontent-length:-1\n\nThe body of the message\0");
 		StompHeaderAccessor headers = StompHeaderAccessor.wrap(message);
 
@@ -121,7 +121,7 @@ public class StompDecoderTests {
 	}
 
 	@Test
-	public void decodeFrameWithContentLengthZero() {
+	void decodeFrameWithContentLengthZero() {
 		Message<byte[]> frame = decode("SEND\ncontent-length:0\n\n\0");
 		StompHeaderAccessor headers = StompHeaderAccessor.wrap(frame);
 
@@ -135,7 +135,7 @@ public class StompDecoderTests {
 	}
 
 	@Test
-	public void decodeFrameWithNullOctectsInTheBody() {
+	void decodeFrameWithNullOctectsInTheBody() {
 		Message<byte[]> frame = decode("SEND\ncontent-length:23\n\nThe b\0dy \0f the message\0");
 		StompHeaderAccessor headers = StompHeaderAccessor.wrap(frame);
 
@@ -149,7 +149,7 @@ public class StompDecoderTests {
 	}
 
 	@Test
-	public void decodeFrameWithEscapedHeaders() {
+	void decodeFrameWithEscapedHeaders() {
 		Message<byte[]> frame = decode("DISCONNECT\na\\c\\r\\n\\\\b:alpha\\cbravo\\r\\n\\\\\n\n\0");
 		StompHeaderAccessor headers = StompHeaderAccessor.wrap(frame);
 
@@ -177,7 +177,7 @@ public class StompDecoderTests {
 	}
 
 	@Test
-	public void decodeFrameBodyNotAllowed() {
+	void decodeFrameBodyNotAllowed() {
 		assertThatExceptionOfType(StompConversionException.class).isThrownBy(() ->
 				decode("CONNECT\naccept-version:1.2\n\nThe body of the message\0"));
 	}
@@ -194,7 +194,7 @@ public class StompDecoderTests {
 	}
 
 	@Test
-	public void decodeMultipleFramesFromSameBuffer() {
+	void decodeMultipleFramesFromSameBuffer() {
 		String frame1 = "SEND\ndestination:test\n\nThe body of the message\0";
 		String frame2 = "DISCONNECT\n\n\0";
 		ByteBuffer buffer = ByteBuffer.wrap((frame1 + frame2).getBytes());
@@ -224,48 +224,48 @@ public class StompDecoderTests {
 	}
 
 	@Test
-	public void decodeFrameWithIncompleteCommand() {
+	void decodeFrameWithIncompleteCommand() {
 		assertIncompleteDecode("MESSAG");
 	}
 
 	@Test
-	public void decodeFrameWithIncompleteHeader() {
+	void decodeFrameWithIncompleteHeader() {
 		assertIncompleteDecode("SEND\ndestination");
 		assertIncompleteDecode("SEND\ndestination:");
 		assertIncompleteDecode("SEND\ndestination:test");
 	}
 
 	@Test
-	public void decodeFrameWithoutNullOctetTerminator() {
+	void decodeFrameWithoutNullOctetTerminator() {
 		assertIncompleteDecode("SEND\ndestination:test\n");
 		assertIncompleteDecode("SEND\ndestination:test\n\n");
 		assertIncompleteDecode("SEND\ndestination:test\n\nThe body");
 	}
 
 	@Test
-	public void decodeFrameWithInsufficientContent() {
+	void decodeFrameWithInsufficientContent() {
 		assertIncompleteDecode("SEND\ncontent-length:23\n\nThe body of the mess");
 	}
 
 	@Test
-	public void decodeFrameWithIncompleteContentType() {
+	void decodeFrameWithIncompleteContentType() {
 		assertIncompleteDecode("SEND\ncontent-type:text/plain;charset=U");
 	}
 
 	@Test
-	public void decodeFrameWithInvalidContentType() {
+	void decodeFrameWithInvalidContentType() {
 		assertThatExceptionOfType(InvalidMimeTypeException.class).isThrownBy(() ->
 				assertIncompleteDecode("SEND\ncontent-type:text/plain;charset=U\n\nThe body\0"));
 	}
 
 	@Test
-	public void decodeFrameWithIncorrectTerminator() {
+	void decodeFrameWithIncorrectTerminator() {
 		assertThatExceptionOfType(StompConversionException.class).isThrownBy(() ->
 				decode("SEND\ncontent-length:23\n\nThe body of the message*"));
 	}
 
 	@Test
-	public void decodeHeartbeat() {
+	void decodeHeartbeat() {
 		String frame = "\n";
 
 		ByteBuffer buffer = ByteBuffer.wrap(frame.getBytes());
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompEncoderTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompEncoderTests.java
index d7f8a169af..b5b4ffd558 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompEncoderTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompEncoderTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,13 +29,13 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Andy Wilkinson
  * @author Stephane Maldini
  */
-public class StompEncoderTests {
+class StompEncoderTests {
 
 	private final StompEncoder encoder = new StompEncoder();
 
 
 	@Test
-	public void encodeFrameWithNoHeadersAndNoBody() {
+	void encodeFrameWithNoHeadersAndNoBody() {
 		StompHeaderAccessor headers = StompHeaderAccessor.create(StompCommand.DISCONNECT);
 		Message<byte[]> frame = MessageBuilder.createMessage(new byte[0], headers.getMessageHeaders());
 
@@ -43,7 +43,7 @@ public class StompEncoderTests {
 	}
 
 	@Test
-	public void encodeFrameWithHeaders() {
+	void encodeFrameWithHeaders() {
 		StompHeaderAccessor headers = StompHeaderAccessor.create(StompCommand.CONNECT);
 		headers.setAcceptVersion("1.2");
 		headers.setHost("github.org");
@@ -55,7 +55,7 @@ public class StompEncoderTests {
 	}
 
 	@Test
-	public void encodeFrameWithHeadersThatShouldBeEscaped() {
+	void encodeFrameWithHeadersThatShouldBeEscaped() {
 		StompHeaderAccessor headers = StompHeaderAccessor.create(StompCommand.DISCONNECT);
 		headers.addNativeHeader("a:\r\n\\b", "alpha:bravo\r\n\\");
 		Message<byte[]> frame = MessageBuilder.createMessage(new byte[0], headers.getMessageHeaders());
@@ -64,7 +64,7 @@ public class StompEncoderTests {
 	}
 
 	@Test
-	public void encodeFrameWithHeadersBody() {
+	void encodeFrameWithHeadersBody() {
 		StompHeaderAccessor headers = StompHeaderAccessor.create(StompCommand.SEND);
 		headers.addNativeHeader("a", "alpha");
 		Message<byte[]> frame = MessageBuilder.createMessage(
@@ -74,7 +74,7 @@ public class StompEncoderTests {
 	}
 
 	@Test
-	public void encodeFrameWithContentLengthPresent() {
+	void encodeFrameWithContentLengthPresent() {
 		StompHeaderAccessor headers = StompHeaderAccessor.create(StompCommand.SEND);
 		headers.setContentLength(12);
 		Message<byte[]> frame = MessageBuilder.createMessage(
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompHeaderAccessorTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompHeaderAccessorTests.java
index b733089fbe..59a2cdc4a1 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompHeaderAccessorTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompHeaderAccessorTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,6 @@
 
 package org.springframework.messaging.simp.stomp;
 
-import java.io.UnsupportedEncodingException;
 import java.nio.charset.StandardCharsets;
 import java.util.List;
 import java.util.Map;
@@ -44,10 +43,10 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Rossen Stoyanchev
  * @since 4.0
  */
-public class StompHeaderAccessorTests {
+class StompHeaderAccessorTests {
 
 	@Test
-	public void createWithCommand() {
+	void createWithCommand() {
 		StompHeaderAccessor accessor = StompHeaderAccessor.create(StompCommand.CONNECTED);
 		assertThat(accessor.getCommand()).isEqualTo(StompCommand.CONNECTED);
 
@@ -56,7 +55,7 @@ public class StompHeaderAccessorTests {
 	}
 
 	@Test
-	public void createWithSubscribeNativeHeaders() {
+	void createWithSubscribeNativeHeaders() {
 		MultiValueMap<String, String> extHeaders = new LinkedMultiValueMap<>();
 		extHeaders.add(StompHeaderAccessor.STOMP_ID_HEADER, "s1");
 		extHeaders.add(StompHeaderAccessor.STOMP_DESTINATION_HEADER, "/d");
@@ -70,7 +69,7 @@ public class StompHeaderAccessorTests {
 	}
 
 	@Test
-	public void createWithUnsubscribeNativeHeaders() {
+	void createWithUnsubscribeNativeHeaders() {
 		MultiValueMap<String, String> extHeaders = new LinkedMultiValueMap<>();
 		extHeaders.add(StompHeaderAccessor.STOMP_ID_HEADER, "s1");
 
@@ -82,7 +81,7 @@ public class StompHeaderAccessorTests {
 	}
 
 	@Test
-	public void createWithMessageFrameNativeHeaders() {
+	void createWithMessageFrameNativeHeaders() {
 		MultiValueMap<String, String> extHeaders = new LinkedMultiValueMap<>();
 		extHeaders.add(StompHeaderAccessor.DESTINATION_HEADER, "/d");
 		extHeaders.add(StompHeaderAccessor.STOMP_SUBSCRIPTION_HEADER, "s1");
@@ -96,7 +95,7 @@ public class StompHeaderAccessorTests {
 	}
 
 	@Test
-	public void createWithConnectNativeHeaders() {
+	void createWithConnectNativeHeaders() {
 		MultiValueMap<String, String> extHeaders = new LinkedMultiValueMap<>();
 		extHeaders.add(StompHeaderAccessor.STOMP_LOGIN_HEADER, "joe");
 		extHeaders.add(StompHeaderAccessor.STOMP_PASSCODE_HEADER, "joe123");
@@ -111,12 +110,12 @@ public class StompHeaderAccessorTests {
 		assertThat(headerAccessor.toString()).contains("passcode=[PROTECTED]");
 
 		Map<String, List<String>> output = headerAccessor.toNativeHeaderMap();
-		assertThat(output.get(StompHeaderAccessor.STOMP_LOGIN_HEADER)).element(0).isEqualTo("joe");
-		assertThat(output.get(StompHeaderAccessor.STOMP_PASSCODE_HEADER)).element(0).isEqualTo("PROTECTED");
+		assertThat(output.get(StompHeaderAccessor.STOMP_LOGIN_HEADER)).containsExactly("joe");
+		assertThat(output.get(StompHeaderAccessor.STOMP_PASSCODE_HEADER)).containsExactly("PROTECTED");
 	}
 
 	@Test
-	public void toNativeHeadersSubscribe() {
+	void toNativeHeadersSubscribe() {
 		StompHeaderAccessor headers = StompHeaderAccessor.create(StompCommand.SUBSCRIBE);
 		headers.setSubscriptionId("s1");
 		headers.setDestination("/d");
@@ -124,23 +123,23 @@ public class StompHeaderAccessorTests {
 		Map<String, List<String>> actual = headers.toNativeHeaderMap();
 
 		assertThat(actual).hasSize(2);
-		assertThat(actual.get(StompHeaderAccessor.STOMP_ID_HEADER)).element(0).isEqualTo("s1");
-		assertThat(actual.get(StompHeaderAccessor.STOMP_DESTINATION_HEADER)).element(0).isEqualTo("/d");
+		assertThat(actual.get(StompHeaderAccessor.STOMP_ID_HEADER)).containsExactly("s1");
+		assertThat(actual.get(StompHeaderAccessor.STOMP_DESTINATION_HEADER)).containsExactly("/d");
 	}
 
 	@Test
-	public void toNativeHeadersUnsubscribe() {
+	void toNativeHeadersUnsubscribe() {
 		StompHeaderAccessor headers = StompHeaderAccessor.create(StompCommand.UNSUBSCRIBE);
 		headers.setSubscriptionId("s1");
 
 		Map<String, List<String>> actual = headers.toNativeHeaderMap();
 
 		assertThat(actual).hasSize(1);
-		assertThat(actual.get(StompHeaderAccessor.STOMP_ID_HEADER)).element(0).isEqualTo("s1");
+		assertThat(actual.get(StompHeaderAccessor.STOMP_ID_HEADER)).containsExactly("s1");
 	}
 
 	@Test
-	public void toNativeHeadersMessageFrame() {
+	void toNativeHeadersMessageFrame() {
 		StompHeaderAccessor headers = StompHeaderAccessor.create(StompCommand.MESSAGE);
 		headers.setSubscriptionId("s1");
 		headers.setDestination("/d");
@@ -150,14 +149,14 @@ public class StompHeaderAccessorTests {
 		Map<String, List<String>> actual = headers.toNativeHeaderMap();
 
 		assertThat(actual.size()).as(actual.toString()).isEqualTo(4);
-		assertThat(actual.get(StompHeaderAccessor.STOMP_SUBSCRIPTION_HEADER)).element(0).isEqualTo("s1");
-		assertThat(actual.get(StompHeaderAccessor.STOMP_DESTINATION_HEADER)).element(0).isEqualTo("/d");
-		assertThat(actual.get(StompHeaderAccessor.STOMP_CONTENT_TYPE_HEADER)).element(0).isEqualTo("application/json");
-		assertThat(actual.get(StompHeaderAccessor.STOMP_MESSAGE_ID_HEADER)).element(0).as("message-id was not created").isNotNull();
+		assertThat(actual.get(StompHeaderAccessor.STOMP_SUBSCRIPTION_HEADER)).containsExactly("s1");
+		assertThat(actual.get(StompHeaderAccessor.STOMP_DESTINATION_HEADER)).containsExactly("/d");
+		assertThat(actual.get(StompHeaderAccessor.STOMP_CONTENT_TYPE_HEADER)).containsExactly("application/json");
+		assertThat(actual.get(StompHeaderAccessor.STOMP_MESSAGE_ID_HEADER)).singleElement().as("message-id was not created").isNotNull();
 	}
 
 	@Test
-	public void toNativeHeadersContentType() {
+	void toNativeHeadersContentType() {
 		SimpMessageHeaderAccessor simpHeaderAccessor = SimpMessageHeaderAccessor.create();
 		simpHeaderAccessor.setContentType(MimeType.valueOf("application/atom+xml"));
 		Message<byte[]> message = MessageBuilder.createMessage(new byte[0], simpHeaderAccessor.getMessageHeaders());
@@ -165,11 +164,11 @@ public class StompHeaderAccessorTests {
 		StompHeaderAccessor stompHeaderAccessor = StompHeaderAccessor.wrap(message);
 		Map<String, List<String>> map = stompHeaderAccessor.toNativeHeaderMap();
 
-		assertThat(map.get(StompHeaderAccessor.STOMP_CONTENT_TYPE_HEADER)).element(0).isEqualTo("application/atom+xml");
+		assertThat(map.get(StompHeaderAccessor.STOMP_CONTENT_TYPE_HEADER)).containsExactly("application/atom+xml");
 	}
 
 	@Test
-	public void encodeConnectWithLoginAndPasscode() throws UnsupportedEncodingException {
+	void encodeConnectWithLoginAndPasscode() {
 		MultiValueMap<String, String> extHeaders = new LinkedMultiValueMap<>();
 		extHeaders.add(StompHeaderAccessor.STOMP_LOGIN_HEADER, "joe");
 		extHeaders.add(StompHeaderAccessor.STOMP_PASSCODE_HEADER, "joe123");
@@ -178,11 +177,11 @@ public class StompHeaderAccessorTests {
 		Message<byte[]> message = MessageBuilder.createMessage(new byte[0], headerAccessor.getMessageHeaders());
 		byte[] bytes = new StompEncoder().encode(message);
 
-		assertThat(new String(bytes, "UTF-8")).isEqualTo("CONNECT\nlogin:joe\npasscode:joe123\n\n\0");
+		assertThat(new String(bytes, StandardCharsets.UTF_8)).isEqualTo("CONNECT\nlogin:joe\npasscode:joe123\n\n\0");
 	}
 
 	@Test
-	public void modifyCustomNativeHeader() {
+	void modifyCustomNativeHeader() {
 		MultiValueMap<String, String> extHeaders = new LinkedMultiValueMap<>();
 		extHeaders.add(StompHeaderAccessor.STOMP_ID_HEADER, "s1");
 		extHeaders.add(StompHeaderAccessor.STOMP_DESTINATION_HEADER, "/d");
@@ -195,13 +194,13 @@ public class StompHeaderAccessorTests {
 		Map<String, List<String>> actual = headers.toNativeHeaderMap();
 		assertThat(actual).hasSize(3);
 
-		assertThat(actual.get(StompHeaderAccessor.STOMP_ID_HEADER)).element(0).isEqualTo("s1");
-		assertThat(actual.get(StompHeaderAccessor.STOMP_DESTINATION_HEADER)).element(0).isEqualTo("/d");
+		assertThat(actual.get(StompHeaderAccessor.STOMP_ID_HEADER)).containsExactly("s1");
+		assertThat(actual.get(StompHeaderAccessor.STOMP_DESTINATION_HEADER)).containsExactly("/d");
 		assertThat(actual.get("accountId")).element(0).as("abc123").isNotNull();
 	}
 
 	@Test
-	public void messageIdAndTimestampDefaultBehavior() {
+	void messageIdAndTimestampDefaultBehavior() {
 		StompHeaderAccessor headerAccessor = StompHeaderAccessor.create(StompCommand.SEND);
 		MessageHeaders headers = headerAccessor.getMessageHeaders();
 
@@ -210,7 +209,7 @@ public class StompHeaderAccessorTests {
 	}
 
 	@Test
-	public void messageIdAndTimestampEnabled() {
+	void messageIdAndTimestampEnabled() {
 		IdTimestampMessageHeaderInitializer headerInitializer = new IdTimestampMessageHeaderInitializer();
 		headerInitializer.setIdGenerator(new AlternativeJdkIdGenerator());
 		headerInitializer.setEnableTimestamp(true);
@@ -223,7 +222,7 @@ public class StompHeaderAccessorTests {
 	}
 
 	@Test
-	public void getAccessor() {
+	void getAccessor() {
 		StompHeaderAccessor headerAccessor = StompHeaderAccessor.create(StompCommand.CONNECT);
 		Message<byte[]> message = MessageBuilder.createMessage(new byte[0], headerAccessor.getMessageHeaders());
 
@@ -231,7 +230,7 @@ public class StompHeaderAccessorTests {
 	}
 
 	@Test
-	public void getShortLogMessage() {
+	void getShortLogMessage() {
 		StompHeaderAccessor accessor = StompHeaderAccessor.create(StompCommand.SEND);
 		accessor.setDestination("/foo");
 		accessor.setContentType(MimeTypeUtils.APPLICATION_JSON);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/user/DefaultUserDestinationResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/user/DefaultUserDestinationResolverTests.java
index 2a0beb610d..b9f1723d3a 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/user/DefaultUserDestinationResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/user/DefaultUserDestinationResolverTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -38,7 +38,7 @@ import static org.mockito.Mockito.mock;
  *
  * @author Rossen Stoyanchev
  */
-public class DefaultUserDestinationResolverTests {
+class DefaultUserDestinationResolverTests {
 
 	private SimpUserRegistry registry = mock();
 
@@ -46,7 +46,7 @@ public class DefaultUserDestinationResolverTests {
 
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 		TestSimpUser simpUser = new TestSimpUser("joe");
 		simpUser.addSessions(new TestSimpSession("123"));
 
@@ -54,7 +54,7 @@ public class DefaultUserDestinationResolverTests {
 	}
 
 	@Test
-	public void handleSubscribe() {
+	void handleSubscribe() {
 		TestPrincipal user = new TestPrincipal("joe");
 		String sourceDestination = "/user/queue/foo";
 
@@ -62,8 +62,7 @@ public class DefaultUserDestinationResolverTests {
 		UserDestinationResult actual = this.resolver.resolveDestination(message);
 
 		assertThat(actual.getSourceDestination()).isEqualTo(sourceDestination);
-		assertThat(actual.getTargetDestinations()).hasSize(1);
-		assertThat(actual.getTargetDestinations()).element(0).isEqualTo("/queue/foo-user123");
+		assertThat(actual.getTargetDestinations()).containsExactly("/queue/foo-user123");
 		assertThat(actual.getSubscribeDestination()).isEqualTo(sourceDestination);
 		assertThat(actual.getUser()).isEqualTo(user.getName());
 	}
@@ -77,8 +76,7 @@ public class DefaultUserDestinationResolverTests {
 		Message<?> message = createMessage(SimpMessageType.SUBSCRIBE, user, "123", destination);
 		UserDestinationResult actual = this.resolver.resolveDestination(message);
 
-		assertThat(actual.getTargetDestinations()).hasSize(1);
-		assertThat(actual.getTargetDestinations()).element(0).isEqualTo("jms.queue.call-user123");
+		assertThat(actual.getTargetDestinations()).containsExactly("jms.queue.call-user123");
 		assertThat(actual.getSubscribeDestination()).isEqualTo(destination);
 	}
 
@@ -93,19 +91,17 @@ public class DefaultUserDestinationResolverTests {
 		Message<?> message = createMessage(SimpMessageType.SUBSCRIBE, user, "456", "/user/queue/foo");
 		UserDestinationResult actual = this.resolver.resolveDestination(message);
 
-		assertThat(actual.getTargetDestinations()).hasSize(1);
-		assertThat(actual.getTargetDestinations()).element(0).isEqualTo("/queue/foo-user456");
+		assertThat(actual.getTargetDestinations()).containsExactly("/queue/foo-user456");
 	}
 
 	@Test
-	public void handleSubscribeNoUser() {
+	void handleSubscribeNoUser() {
 		String sourceDestination = "/user/queue/foo";
 		Message<?> message = createMessage(SimpMessageType.SUBSCRIBE, null, "123", sourceDestination);
 		UserDestinationResult actual = this.resolver.resolveDestination(message);
 
 		assertThat(actual.getSourceDestination()).isEqualTo(sourceDestination);
-		assertThat(actual.getTargetDestinations()).hasSize(1);
-		assertThat(actual.getTargetDestinations()).element(0).isEqualTo(("/queue/foo-user" + "123"));
+		assertThat(actual.getTargetDestinations()).containsExactly("/queue/foo-user" + "123");
 		assertThat(actual.getSubscribeDestination()).isEqualTo(sourceDestination);
 		assertThat(actual.getUser()).isNull();
 	}
@@ -120,25 +116,23 @@ public class DefaultUserDestinationResolverTests {
 	}
 
 	@Test
-	public void handleUnsubscribe() {
+	void handleUnsubscribe() {
 		TestPrincipal user = new TestPrincipal("joe");
 		Message<?> message = createMessage(SimpMessageType.UNSUBSCRIBE, user, "123", "/user/queue/foo");
 		UserDestinationResult actual = this.resolver.resolveDestination(message);
 
-		assertThat(actual.getTargetDestinations()).hasSize(1);
-		assertThat(actual.getTargetDestinations()).element(0).isEqualTo("/queue/foo-user123");
+		assertThat(actual.getTargetDestinations()).containsExactly("/queue/foo-user123");
 	}
 
 	@Test
-	public void handleMessage() {
+	void handleMessage() {
 		TestPrincipal user = new TestPrincipal("joe");
 		String sourceDestination = "/user/joe/queue/foo";
 		Message<?> message = createMessage(SimpMessageType.MESSAGE, user, "123", sourceDestination);
 		UserDestinationResult actual = this.resolver.resolveDestination(message);
 
 		assertThat(actual.getSourceDestination()).isEqualTo(sourceDestination);
-		assertThat(actual.getTargetDestinations()).hasSize(1);
-		assertThat(actual.getTargetDestinations()).element(0).isEqualTo("/queue/foo-user123");
+		assertThat(actual.getTargetDestinations()).containsExactly("/queue/foo-user123");
 		assertThat(actual.getSubscribeDestination()).isEqualTo("/user/queue/foo");
 		assertThat(actual.getUser()).isEqualTo(user.getName());
 	}
@@ -152,8 +146,7 @@ public class DefaultUserDestinationResolverTests {
 		Message<?> message = createMessage(SimpMessageType.MESSAGE, user, "123", destination);
 		UserDestinationResult actual = this.resolver.resolveDestination(message);
 
-		assertThat(actual.getTargetDestinations()).hasSize(1);
-		assertThat(actual.getTargetDestinations()).element(0).isEqualTo("jms.queue.call-user123");
+		assertThat(actual.getTargetDestinations()).containsExactly("jms.queue.call-user123");
 		assertThat(actual.getSubscribeDestination()).isEqualTo("/user/jms.queue.call");
 	}
 
@@ -172,14 +165,13 @@ public class DefaultUserDestinationResolverTests {
 		UserDestinationResult actual = this.resolver.resolveDestination(message);
 
 		assertThat(actual.getSourceDestination()).isEqualTo(sourceDestination);
-		assertThat(actual.getTargetDestinations()).hasSize(1);
-		assertThat(actual.getTargetDestinations()).element(0).isEqualTo("/queue/foo-user456");
+		assertThat(actual.getTargetDestinations()).containsExactly("/queue/foo-user456");
 		assertThat(actual.getSubscribeDestination()).isEqualTo("/user/queue/foo");
 		assertThat(actual.getUser()).isEqualTo(otherUser.getName());
 	}
 
 	@Test
-	public void handleMessageEncodedUserName() {
+	void handleMessageEncodedUserName() {
 		String userName = "https://joe.openid.example.org/";
 
 		TestSimpUser simpUser = new TestSimpUser(userName);
@@ -191,25 +183,23 @@ public class DefaultUserDestinationResolverTests {
 		Message<?> message = createMessage(SimpMessageType.MESSAGE, new TestPrincipal("joe"), null, destination);
 		UserDestinationResult actual = this.resolver.resolveDestination(message);
 
-		assertThat(actual.getTargetDestinations()).hasSize(1);
-		assertThat(actual.getTargetDestinations()).element(0).isEqualTo("/queue/foo-useropenid123");
+		assertThat(actual.getTargetDestinations()).containsExactly("/queue/foo-useropenid123");
 	}
 
 	@Test
-	public void handleMessageWithNoUser() {
+	void handleMessageWithNoUser() {
 		String sourceDestination = "/user/" + "123" + "/queue/foo";
 		Message<?> message = createMessage(SimpMessageType.MESSAGE, null, "123", sourceDestination);
 		UserDestinationResult actual = this.resolver.resolveDestination(message);
 
 		assertThat(actual.getSourceDestination()).isEqualTo(sourceDestination);
-		assertThat(actual.getTargetDestinations()).hasSize(1);
-		assertThat(actual.getTargetDestinations()).element(0).isEqualTo("/queue/foo-user123");
+		assertThat(actual.getTargetDestinations()).containsExactly("/queue/foo-user123");
 		assertThat(actual.getSubscribeDestination()).isEqualTo("/user/queue/foo");
 		assertThat(actual.getUser()).isNull();
 	}
 
 	@Test
-	public void ignoreMessage() {
+	void ignoreMessage() {
 
 		// no destination
 		TestPrincipal user = new TestPrincipal("joe");
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/user/UserRegistryMessageHandlerTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/user/UserRegistryMessageHandlerTests.java
index e16709f042..4c9c4f6717 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/simp/user/UserRegistryMessageHandlerTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/user/UserRegistryMessageHandlerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -65,7 +65,7 @@ class UserRegistryMessageHandlerTests {
 
 
 	@BeforeEach
-	void setUp() throws Exception {
+	void setUp() {
 		SimpMessagingTemplate brokerTemplate = new SimpMessagingTemplate(this.brokerChannel);
 		brokerTemplate.setMessageConverter(this.converter);
 
@@ -74,14 +74,14 @@ class UserRegistryMessageHandlerTests {
 	}
 
 	@Test
-	void brokerAvailableEvent() throws Exception {
+	void brokerAvailableEvent() {
 		Runnable runnable = getUserRegistryTask();
 		assertThat(runnable).isNotNull();
 	}
 
 	@Test
 	@SuppressWarnings({ "unchecked", "rawtypes" })
-	void brokerUnavailableEvent() throws Exception {
+	void brokerUnavailableEvent() {
 		ScheduledFuture future = mock();
 		given(this.taskScheduler.scheduleWithFixedDelay(any(Runnable.class), any(Duration.class))).willReturn(future);
 
@@ -96,7 +96,7 @@ class UserRegistryMessageHandlerTests {
 
 	@Test
 	@SuppressWarnings("rawtypes")
-	void broadcastRegistry() throws Exception {
+	void broadcastRegistry() {
 		given(this.brokerChannel.send(any())).willReturn(true);
 
 		TestSimpUser simpUser1 = new TestSimpUser("joe");
@@ -126,7 +126,7 @@ class UserRegistryMessageHandlerTests {
 	}
 
 	@Test
-	void handleMessage() throws Exception {
+	void handleMessage() {
 		TestSimpUser simpUser1 = new TestSimpUser("joe");
 		TestSimpUser simpUser2 = new TestSimpUser("jane");
 
@@ -149,7 +149,7 @@ class UserRegistryMessageHandlerTests {
 	}
 
 	@Test
-	void handleMessageFromOwnBroadcast() throws Exception {
+	void handleMessageFromOwnBroadcast() {
 		TestSimpUser simpUser = new TestSimpUser("joe");
 		simpUser.addSessions(new TestSimpSession("123"));
 		given(this.localRegistry.getUserCount()).willReturn(1);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/support/ChannelInterceptorTests.java b/spring-messaging/src/test/java/org/springframework/messaging/support/ChannelInterceptorTests.java
index 891684fd4c..73f95c50d6 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/support/ChannelInterceptorTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/support/ChannelInterceptorTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,7 +37,7 @@ import static org.mockito.Mockito.mock;
  *
  * @author Rossen Stoyanchev
  */
-public class ChannelInterceptorTests {
+class ChannelInterceptorTests {
 
 	private ExecutorSubscribableChannel channel;
 
@@ -45,7 +45,7 @@ public class ChannelInterceptorTests {
 
 
 	@BeforeEach
-	public void setup() {
+	void setup() {
 		this.channel = new ExecutorSubscribableChannel();
 		this.messageHandler = new TestMessageHandler();
 		this.channel.subscribe(this.messageHandler);
@@ -53,7 +53,7 @@ public class ChannelInterceptorTests {
 
 
 	@Test
-	public void preSendInterceptorReturningModifiedMessage() {
+	void preSendInterceptorReturningModifiedMessage() {
 		Message<?> expected = mock();
 		PreSendInterceptor interceptor = new PreSendInterceptor();
 		interceptor.setMessageToReturn(expected);
@@ -69,7 +69,7 @@ public class ChannelInterceptorTests {
 	}
 
 	@Test
-	public void preSendInterceptorReturningNull() {
+	void preSendInterceptorReturningNull() {
 		PreSendInterceptor interceptor1 = new PreSendInterceptor();
 		NullReturningPreSendInterceptor interceptor2 = new NullReturningPreSendInterceptor();
 		this.channel.addInterceptor(interceptor1);
@@ -85,7 +85,7 @@ public class ChannelInterceptorTests {
 	}
 
 	@Test
-	public void postSendInterceptorMessageWasSent() {
+	void postSendInterceptorMessageWasSent() {
 		final AtomicBoolean preSendInvoked = new AtomicBoolean();
 		final AtomicBoolean completionInvoked = new AtomicBoolean();
 		this.channel.addInterceptor(new ChannelInterceptor() {
@@ -112,7 +112,7 @@ public class ChannelInterceptorTests {
 	}
 
 	@Test
-	public void postSendInterceptorMessageWasNotSent() {
+	void postSendInterceptorMessageWasNotSent() {
 		final AbstractMessageChannel testChannel = new AbstractMessageChannel() {
 			@Override
 			protected boolean sendInternal(Message<?> message, long timeout) {
@@ -145,7 +145,7 @@ public class ChannelInterceptorTests {
 	}
 
 	@Test
-	public void afterCompletionWithSendException() {
+	void afterCompletionWithSendException() {
 		final AbstractMessageChannel testChannel = new AbstractMessageChannel() {
 			@Override
 			protected boolean sendInternal(Message<?> message, long timeout) {
@@ -167,7 +167,7 @@ public class ChannelInterceptorTests {
 	}
 
 	@Test
-	public void afterCompletionWithPreSendException() {
+	void afterCompletionWithPreSendException() {
 		PreSendInterceptor interceptor1 = new PreSendInterceptor();
 		PreSendInterceptor interceptor2 = new PreSendInterceptor();
 		interceptor2.setExceptionToRaise(new RuntimeException("Simulated exception"));
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/support/ErrorMessageTests.java b/spring-messaging/src/test/java/org/springframework/messaging/support/ErrorMessageTests.java
index 9ac44ce2c1..58e6ab5b5c 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/support/ErrorMessageTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/support/ErrorMessageTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,10 +25,10 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Gary Russell
  * @since 5.0
  */
-public class ErrorMessageTests {
+class ErrorMessageTests {
 
 	@Test
-	public void testToString() {
+	void testToString() {
 		ErrorMessage em = new ErrorMessage(new RuntimeException("foo"));
 		String emString = em.toString();
 		assertThat(emString).doesNotContain("original");
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/support/ExecutorSubscribableChannelTests.java b/spring-messaging/src/test/java/org/springframework/messaging/support/ExecutorSubscribableChannelTests.java
index 096df45de7..60125a7df8 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/support/ExecutorSubscribableChannelTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/support/ExecutorSubscribableChannelTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -63,14 +63,14 @@ public class ExecutorSubscribableChannelTests {
 
 
 	@Test
-	public void messageMustNotBeNull() {
+	void messageMustNotBeNull() {
 		assertThatIllegalArgumentException().isThrownBy(() ->
 				this.channel.send(null))
 			.withMessageContaining("Message must not be null");
 	}
 
 	@Test
-	public void sendWithoutExecutor() {
+	void sendWithoutExecutor() {
 		BeforeHandleInterceptor interceptor = new BeforeHandleInterceptor();
 		this.channel.addInterceptor(interceptor);
 		this.channel.subscribe(this.handler);
@@ -81,7 +81,7 @@ public class ExecutorSubscribableChannelTests {
 	}
 
 	@Test
-	public void sendWithExecutor() {
+	void sendWithExecutor() {
 		BeforeHandleInterceptor interceptor = new BeforeHandleInterceptor();
 		TaskExecutor executor = mock();
 		ExecutorSubscribableChannel testChannel = new ExecutorSubscribableChannel(executor);
@@ -97,7 +97,7 @@ public class ExecutorSubscribableChannelTests {
 	}
 
 	@Test
-	public void subscribeTwice() {
+	void subscribeTwice() {
 		assertThat(this.channel.subscribe(this.handler)).isTrue();
 		assertThat(this.channel.subscribe(this.handler)).isFalse();
 		this.channel.send(this.message);
@@ -105,7 +105,7 @@ public class ExecutorSubscribableChannelTests {
 	}
 
 	@Test
-	public void unsubscribeTwice() {
+	void unsubscribeTwice() {
 		this.channel.subscribe(this.handler);
 		assertThat(this.channel.unsubscribe(this.handler)).isTrue();
 		assertThat(this.channel.unsubscribe(this.handler)).isFalse();
@@ -114,7 +114,7 @@ public class ExecutorSubscribableChannelTests {
 	}
 
 	@Test
-	public void failurePropagates() {
+	void failurePropagates() {
 		RuntimeException ex = new RuntimeException();
 		willThrow(ex).given(this.handler).handleMessage(this.message);
 		MessageHandler secondHandler = mock();
@@ -130,7 +130,7 @@ public class ExecutorSubscribableChannelTests {
 	}
 
 	@Test
-	public void concurrentModification() {
+	void concurrentModification() {
 		this.channel.subscribe(message1 -> channel.unsubscribe(handler));
 		this.channel.subscribe(this.handler);
 		this.channel.send(this.message);
@@ -138,7 +138,7 @@ public class ExecutorSubscribableChannelTests {
 	}
 
 	@Test
-	public void interceptorWithModifiedMessage() {
+	void interceptorWithModifiedMessage() {
 		Message<?> expected = mock();
 		BeforeHandleInterceptor interceptor = new BeforeHandleInterceptor();
 		interceptor.setMessageToReturn(expected);
@@ -151,7 +151,7 @@ public class ExecutorSubscribableChannelTests {
 	}
 
 	@Test
-	public void interceptorWithNull() {
+	void interceptorWithNull() {
 		BeforeHandleInterceptor interceptor1 = new BeforeHandleInterceptor();
 		NullReturningBeforeHandleInterceptor interceptor2 = new NullReturningBeforeHandleInterceptor();
 		this.channel.addInterceptor(interceptor1);
@@ -165,7 +165,7 @@ public class ExecutorSubscribableChannelTests {
 	}
 
 	@Test
-	public void interceptorWithException() {
+	void interceptorWithException() {
 		IllegalStateException expected = new IllegalStateException("Fake exception");
 		willThrow(expected).given(this.handler).handleMessage(this.message);
 		BeforeHandleInterceptor interceptor = new BeforeHandleInterceptor();
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/support/MessageBuilderTests.java b/spring-messaging/src/test/java/org/springframework/messaging/support/MessageBuilderTests.java
index 02d13091f9..42aae2a371 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/support/MessageBuilderTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/support/MessageBuilderTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -150,28 +150,28 @@ class MessageBuilderTests {
 	}
 
 	@Test
-	void notModifiedSameMessage() throws Exception {
+	void notModifiedSameMessage() {
 		Message<?> original = MessageBuilder.withPayload("foo").build();
 		Message<?> result = MessageBuilder.fromMessage(original).build();
 		assertThat(result).isEqualTo(original);
 	}
 
 	@Test
-	void containsHeaderNotModifiedSameMessage() throws Exception {
+	void containsHeaderNotModifiedSameMessage() {
 		Message<?> original = MessageBuilder.withPayload("foo").setHeader("bar", 42).build();
 		Message<?> result = MessageBuilder.fromMessage(original).build();
 		assertThat(result).isEqualTo(original);
 	}
 
 	@Test
-	void sameHeaderValueAddedNotModifiedSameMessage() throws Exception {
+	void sameHeaderValueAddedNotModifiedSameMessage() {
 		Message<?> original = MessageBuilder.withPayload("foo").setHeader("bar", 42).build();
 		Message<?> result = MessageBuilder.fromMessage(original).setHeader("bar", 42).build();
 		assertThat(result).isEqualTo(original);
 	}
 
 	@Test
-	void copySameHeaderValuesNotModifiedSameMessage() throws Exception {
+	void copySameHeaderValuesNotModifiedSameMessage() {
 		Date current = new Date();
 		Map<String, Object> originalHeaders = new HashMap<>();
 		originalHeaders.put("b", "xyz");
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/support/MessageHeaderAccessorTests.java b/spring-messaging/src/test/java/org/springframework/messaging/support/MessageHeaderAccessorTests.java
index 04c013d95d..afe8edea4c 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/support/MessageHeaderAccessorTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/support/MessageHeaderAccessorTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,16 +39,16 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  * @author Sebastien Deleuze
  * @author Juergen Hoeller
  */
-public class MessageHeaderAccessorTests {
+class MessageHeaderAccessorTests {
 
 	@Test
-	public void newEmptyHeaders() {
+	void newEmptyHeaders() {
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 		assertThat(accessor.toMap()).isEmpty();
 	}
 
 	@Test
-	public void existingHeaders() throws InterruptedException {
+	void existingHeaders() {
 		Map<String, Object> map = new HashMap<>();
 		map.put("foo", "bar");
 		map.put("bar", "baz");
@@ -63,7 +63,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void existingHeadersModification() throws InterruptedException {
+	void existingHeadersModification() throws InterruptedException {
 		Map<String, Object> map = new HashMap<>();
 		map.put("foo", "bar");
 		map.put("bar", "baz");
@@ -82,7 +82,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void testRemoveHeader() {
+	void testRemoveHeader() {
 		Message<?> message = new GenericMessage<>("payload", Collections.singletonMap("foo", "bar"));
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor(message);
 		accessor.removeHeader("foo");
@@ -91,7 +91,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void testRemoveHeaderEvenIfNull() {
+	void testRemoveHeaderEvenIfNull() {
 		Message<?> message = new GenericMessage<>("payload", Collections.singletonMap("foo", null));
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor(message);
 		accessor.removeHeader("foo");
@@ -100,7 +100,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void removeHeaders() {
+	void removeHeaders() {
 		Map<String, Object> map = new HashMap<>();
 		map.put("foo", "bar");
 		map.put("bar", "baz");
@@ -116,7 +116,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void copyHeaders() {
+	void copyHeaders() {
 		Map<String, Object> map1 = new HashMap<>();
 		map1.put("foo", "bar");
 		GenericMessage<String> message = new GenericMessage<>("payload", map1);
@@ -134,7 +134,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void copyHeadersIfAbsent() {
+	void copyHeadersIfAbsent() {
 		Map<String, Object> map1 = new HashMap<>();
 		map1.put("foo", "bar");
 		GenericMessage<String> message = new GenericMessage<>("payload", map1);
@@ -152,7 +152,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void copyHeadersFromNullMap() {
+	void copyHeadersFromNullMap() {
 		MessageHeaderAccessor headers = new MessageHeaderAccessor();
 		headers.copyHeaders(null);
 		headers.copyHeadersIfAbsent(null);
@@ -161,7 +161,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void toMap() {
+	void toMap() {
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 
 		accessor.setHeader("foo", "bar1");
@@ -183,7 +183,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void leaveMutable() {
+	void leaveMutable() {
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 		accessor.setHeader("foo", "bar");
 		accessor.setLeaveMutable(true);
@@ -197,7 +197,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void leaveMutableDefaultBehavior() {
+	void leaveMutableDefaultBehavior() {
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 		accessor.setHeader("foo", "bar");
 		MessageHeaders headers = accessor.getMessageHeaders();
@@ -216,14 +216,14 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void getAccessor() {
+	void getAccessor() {
 		MessageHeaderAccessor expected = new MessageHeaderAccessor();
 		Message<?> message = MessageBuilder.createMessage("payload", expected.getMessageHeaders());
 		assertThat(MessageHeaderAccessor.getAccessor(message, MessageHeaderAccessor.class)).isSameAs(expected);
 	}
 
 	@Test
-	public void getMutableAccessorSameInstance() {
+	void getMutableAccessorSameInstance() {
 		TestMessageHeaderAccessor expected = new TestMessageHeaderAccessor();
 		expected.setLeaveMutable(true);
 		Message<?> message = MessageBuilder.createMessage("payload", expected.getMessageHeaders());
@@ -235,7 +235,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void getMutableAccessorNewInstance() {
+	void getMutableAccessorNewInstance() {
 		Message<?> message = MessageBuilder.withPayload("payload").build();
 
 		MessageHeaderAccessor actual = MessageHeaderAccessor.getMutableAccessor(message);
@@ -244,7 +244,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void getMutableAccessorNewInstanceMatchingType() {
+	void getMutableAccessorNewInstanceMatchingType() {
 		TestMessageHeaderAccessor expected = new TestMessageHeaderAccessor();
 		Message<?> message = MessageBuilder.createMessage("payload", expected.getMessageHeaders());
 
@@ -255,20 +255,20 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void timestampEnabled() {
+	void timestampEnabled() {
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 		accessor.setEnableTimestamp(true);
 		assertThat(accessor.getMessageHeaders().getTimestamp()).isNotNull();
 	}
 
 	@Test
-	public void timestampDefaultBehavior() {
+	void timestampDefaultBehavior() {
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 		assertThat(accessor.getMessageHeaders().getTimestamp()).isNull();
 	}
 
 	@Test
-	public void idGeneratorCustom() {
+	void idGeneratorCustom() {
 		final UUID id = new UUID(0L, 23L);
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 		accessor.setIdGenerator(() -> id);
@@ -276,14 +276,14 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void idGeneratorDefaultBehavior() {
+	void idGeneratorDefaultBehavior() {
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 		assertThat(accessor.getMessageHeaders().getId()).isNotNull();
 	}
 
 
 	@Test
-	public void idTimestampWithMutableHeaders() {
+	void idTimestampWithMutableHeaders() {
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 		accessor.setIdGenerator(() -> MessageHeaders.ID_VALUE_NONE);
 		accessor.setEnableTimestamp(false);
@@ -303,7 +303,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void getShortLogMessagePayload() {
+	void getShortLogMessagePayload() {
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 		accessor.setContentType(MimeTypeUtils.TEXT_PLAIN);
 
@@ -319,7 +319,7 @@ public class MessageHeaderAccessorTests {
 
 		StringBuilder sb = new StringBuilder();
 		sb.append("a".repeat(80));
-		final String payload = sb.toString() + " > 80";
+		final String payload = sb + " > 80";
 
 		String actual = accessor.getShortLogMessage(payload);
 		assertThat(actual).isEqualTo("headers={contentType=text/plain} payload=" + sb + "...(truncated)");
@@ -337,7 +337,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void getDetailedLogMessagePayload() {
+	void getDetailedLogMessagePayload() {
 		MessageHeaderAccessor accessor = new MessageHeaderAccessor();
 		accessor.setContentType(MimeTypeUtils.TEXT_PLAIN);
 
@@ -371,7 +371,7 @@ public class MessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void serializeMutableHeaders() throws Exception {
+	void serializeMutableHeaders() throws Exception {
 		Map<String, Object> headers = new HashMap<>();
 		headers.put("foo", "bar");
 		Message<String> message = new GenericMessage<>("test", headers);
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/support/NativeMessageHeaderAccessorTests.java b/spring-messaging/src/test/java/org/springframework/messaging/support/NativeMessageHeaderAccessorTests.java
index 3e33820686..7578b5a088 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/support/NativeMessageHeaderAccessorTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/support/NativeMessageHeaderAccessorTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,10 +36,10 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  *
  * @author Rossen Stoyanchev
  */
-public class NativeMessageHeaderAccessorTests {
+class NativeMessageHeaderAccessorTests {
 
 	@Test
-	public void createFromNativeHeaderMap() {
+	void createFromNativeHeaderMap() {
 		MultiValueMap<String, String> inputNativeHeaders = new LinkedMultiValueMap<>();
 		inputNativeHeaders.add("foo", "bar");
 		inputNativeHeaders.add("bar", "baz");
@@ -54,7 +54,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void createFromMessage() {
+	void createFromMessage() {
 		MultiValueMap<String, String> inputNativeHeaders = new LinkedMultiValueMap<>();
 		inputNativeHeaders.add("foo", "bar");
 		inputNativeHeaders.add("bar", "baz");
@@ -75,7 +75,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void createFromMessageNull() {
+	void createFromMessageNull() {
 		NativeMessageHeaderAccessor headerAccessor = new NativeMessageHeaderAccessor((Message<?>) null);
 
 		Map<String, Object> actual = headerAccessor.toMap();
@@ -86,7 +86,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void createFromMessageAndModify() {
+	void createFromMessageAndModify() {
 
 		MultiValueMap<String, String> inputNativeHeaders = new LinkedMultiValueMap<>();
 		inputNativeHeaders.add("foo", "bar");
@@ -117,7 +117,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void setNativeHeader() {
+	void setNativeHeader() {
 		MultiValueMap<String, String> nativeHeaders = new LinkedMultiValueMap<>();
 		nativeHeaders.add("foo", "bar");
 
@@ -128,7 +128,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void setNativeHeaderNullValue() {
+	void setNativeHeaderNullValue() {
 		MultiValueMap<String, String> nativeHeaders = new LinkedMultiValueMap<>();
 		nativeHeaders.add("foo", "bar");
 
@@ -139,7 +139,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void setNativeHeaderLazyInit() {
+	void setNativeHeaderLazyInit() {
 		NativeMessageHeaderAccessor headerAccessor = new NativeMessageHeaderAccessor();
 		headerAccessor.setNativeHeader("foo", "baz");
 
@@ -147,7 +147,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void setNativeHeaderLazyInitNullValue() {
+	void setNativeHeaderLazyInitNullValue() {
 		NativeMessageHeaderAccessor headerAccessor = new NativeMessageHeaderAccessor();
 		headerAccessor.setNativeHeader("foo", null);
 
@@ -156,7 +156,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void setNativeHeaderImmutable() {
+	void setNativeHeaderImmutable() {
 		NativeMessageHeaderAccessor headerAccessor = new NativeMessageHeaderAccessor();
 		headerAccessor.setNativeHeader("foo", "bar");
 		headerAccessor.setImmutable();
@@ -167,7 +167,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void addNativeHeader() {
+	void addNativeHeader() {
 		MultiValueMap<String, String> nativeHeaders = new LinkedMultiValueMap<>();
 		nativeHeaders.add("foo", "bar");
 
@@ -178,7 +178,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void addNativeHeaderNullValue() {
+	void addNativeHeaderNullValue() {
 		MultiValueMap<String, String> nativeHeaders = new LinkedMultiValueMap<>();
 		nativeHeaders.add("foo", "bar");
 
@@ -189,7 +189,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void addNativeHeaderLazyInit() {
+	void addNativeHeaderLazyInit() {
 		NativeMessageHeaderAccessor headerAccessor = new NativeMessageHeaderAccessor();
 		headerAccessor.addNativeHeader("foo", "bar");
 
@@ -197,7 +197,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void addNativeHeaderLazyInitNullValue() {
+	void addNativeHeaderLazyInitNullValue() {
 		NativeMessageHeaderAccessor headerAccessor = new NativeMessageHeaderAccessor();
 		headerAccessor.addNativeHeader("foo", null);
 
@@ -206,7 +206,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void addNativeHeaderImmutable() {
+	void addNativeHeaderImmutable() {
 		NativeMessageHeaderAccessor headerAccessor = new NativeMessageHeaderAccessor();
 		headerAccessor.addNativeHeader("foo", "bar");
 		headerAccessor.setImmutable();
@@ -217,7 +217,7 @@ public class NativeMessageHeaderAccessorTests {
 	}
 
 	@Test
-	public void setImmutableIdempotent() {
+	void setImmutableIdempotent() {
 		NativeMessageHeaderAccessor headerAccessor = new NativeMessageHeaderAccessor();
 		headerAccessor.addNativeHeader("foo", "bar");
 		headerAccessor.setImmutable();