diff --git a/spring-pulsar/src/test/java/org/springframework/pulsar/listener/DefaultPulsarMessageListenerContainerTests.java b/spring-pulsar/src/test/java/org/springframework/pulsar/listener/DefaultPulsarMessageListenerContainerTests.java
index 13f59f74..fa6861c5 100644
--- a/spring-pulsar/src/test/java/org/springframework/pulsar/listener/DefaultPulsarMessageListenerContainerTests.java
+++ b/spring-pulsar/src/test/java/org/springframework/pulsar/listener/DefaultPulsarMessageListenerContainerTests.java
@@ -28,7 +28,6 @@ import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -66,11 +65,9 @@ class DefaultPulsarMessageListenerContainerTests implements PulsarTestContainerS
 
 	@Test
 	void basicDefaultConsumer() throws Exception {
-		Map<String, Object> config = new HashMap<>();
-		HashSet<String> strings = new HashSet<>();
-		strings.add("dpmlct-012");
-		config.put("topicNames", strings);
-		config.put("subscriptionName", "dpmlct-sb-012");
+		Set<String> topics = Collections.singleton("dpmlct-012");
+		Map<String, Object> config = Map.of("topicNames", topics, "subscriptionName", "dpmlct-sb-012");
+
 		PulsarClient pulsarClient = PulsarClient.builder().serviceUrl(PulsarTestContainerSupport.getPulsarBrokerUrl())
 				.build();
 		DefaultPulsarConsumerFactory<String> pulsarConsumerFactory = new DefaultPulsarConsumerFactory<>(pulsarClient,
@@ -100,6 +97,7 @@ class DefaultPulsarMessageListenerContainerTests implements PulsarTestContainerS
 		Set<String> topics = Collections.singleton("containerPauseResumeWaitNotify-topic");
 		Map<String, Object> config = Map.of("topicNames", topics, "subscriptionName",
 				"containerPauseResumeWaitNotify-sub");
+
 		PulsarClient pulsarClient = PulsarClient.builder().serviceUrl(PulsarTestContainerSupport.getPulsarBrokerUrl())
 				.build();
 		DefaultPulsarConsumerFactory<String> pulsarConsumerFactory = new DefaultPulsarConsumerFactory<>(pulsarClient,
@@ -166,12 +164,10 @@ class DefaultPulsarMessageListenerContainerTests implements PulsarTestContainerS
 
 	@Test
 	void subscriptionInitialPositionEarliest() throws Exception {
-		Map<String, Object> config = new HashMap<>();
-		HashSet<String> strings = new HashSet<>();
-		strings.add("dpmlct-013");
-		config.put("topicNames", strings);
-		config.put("subscriptionName", "dpmlct-sb-013");
-		config.put("subscriptionInitialPosition", SubscriptionInitialPosition.Earliest);
+		Set<String> topics = Collections.singleton("dpmlct-013");
+		Map<String, Object> config = Map.of("topicNames", topics, "subscriptionName", "dpmlct-sb-013",
+				"subscriptionInitialPosition", SubscriptionInitialPosition.Earliest);
+
 		PulsarClient pulsarClient = PulsarClient.builder().serviceUrl(PulsarTestContainerSupport.getPulsarBrokerUrl())
 				.build();
 		DefaultPulsarConsumerFactory<String> pulsarConsumerFactory = new DefaultPulsarConsumerFactory<>(pulsarClient,
@@ -201,11 +197,9 @@ class DefaultPulsarMessageListenerContainerTests implements PulsarTestContainerS
 
 	@Test
 	void subscriptionInitialPositionDefaultLatest() throws Exception {
-		Map<String, Object> config = new HashMap<>();
-		HashSet<String> strings = new HashSet<>();
-		strings.add("dpmlct-014");
-		config.put("topicNames", strings);
-		config.put("subscriptionName", "dpmlct-sb-014");
+		Set<String> topics = Collections.singleton("dpmlct-014");
+		Map<String, Object> config = Map.of("topicNames", topics, "subscriptionName", "dpmlct-sb-014");
+
 		PulsarClient pulsarClient = PulsarClient.builder().serviceUrl(PulsarTestContainerSupport.getPulsarBrokerUrl())
 				.build();
 		DefaultPulsarConsumerFactory<String> pulsarConsumerFactory = new DefaultPulsarConsumerFactory<>(pulsarClient,
@@ -238,13 +232,11 @@ class DefaultPulsarMessageListenerContainerTests implements PulsarTestContainerS
 
 	@Test
 	void negativeAckRedeliveryBackoff() throws Exception {
-		Map<String, Object> config = new HashMap<>();
-		config.put("topicNames", Collections.singleton("dpmlct-015"));
-		config.put("subscriptionName", "dpmlct-sb-015");
-
+		Set<String> topics = Collections.singleton("dpmlct-015");
 		RedeliveryBackoff redeliveryBackoff = MultiplierRedeliveryBackoff.builder().minDelayMs(1000)
 				.maxDelayMs(5 * 1000).build();
-		config.put("negativeAckRedeliveryBackoff", redeliveryBackoff);
+		Map<String, Object> config = Map.of("topicNames", topics, "subscriptionName", "dpmlct-sb-015",
+				"negativeAckRedeliveryBackoff", redeliveryBackoff);
 
 		PulsarClient pulsarClient = PulsarClient.builder().serviceUrl(PulsarTestContainerSupport.getPulsarBrokerUrl())
 				.build();
@@ -288,13 +280,11 @@ class DefaultPulsarMessageListenerContainerTests implements PulsarTestContainerS
 
 	@Test
 	void deadLetterPolicyDefault() throws Exception {
-		Map<String, Object> config = new HashMap<>();
-		config.put("topicNames", Collections.singleton("dpmlct-016"));
-		config.put("subscriptionName", "dpmlct-sb-016");
-		config.put("ackTimeoutMillis", 1);
+		Set<String> topics = Collections.singleton("dpmlct-016");
 		DeadLetterPolicy deadLetterPolicy = DeadLetterPolicy.builder().maxRedeliverCount(1)
 				.deadLetterTopic("dpmlct-016-dlq-topic").build();
-		config.put("deadLetterPolicy", deadLetterPolicy);
+		Map<String, Object> config = Map.of("topicNames", topics, "subscriptionName", "dpmlct-sb-016",
+				"ackTimeoutMillis", 1, "deadLetterPolicy", deadLetterPolicy);
 
 		PulsarClient pulsarClient = PulsarClient.builder().serviceUrl(PulsarTestContainerSupport.getPulsarBrokerUrl())
 				.build();
@@ -346,13 +336,11 @@ class DefaultPulsarMessageListenerContainerTests implements PulsarTestContainerS
 
 	@Test
 	void deadLetterPolicyCustom() throws Exception {
-		Map<String, Object> config = new HashMap<>();
-		config.put("topicNames", Collections.singleton("dpmlct-016"));
-		config.put("subscriptionName", "dpmlct-sb-016");
-		config.put("ackTimeoutMillis", 1);
+		Set<String> topics = Collections.singleton("dpmlct-017");
 		DeadLetterPolicy deadLetterPolicy = DeadLetterPolicy.builder().maxRedeliverCount(5).deadLetterTopic("dlq-topic")
 				.build();
-		config.put("deadLetterPolicy", deadLetterPolicy);
+		Map<String, Object> config = Map.of("topicNames", topics, "subscriptionName", "dpmlct-sb-016",
+				"ackTimeoutMillis", 1, "deadLetterPolicy", deadLetterPolicy);
 
 		PulsarClient pulsarClient = PulsarClient.builder().serviceUrl(PulsarTestContainerSupport.getPulsarBrokerUrl())
 				.build();
@@ -388,7 +376,7 @@ class DefaultPulsarMessageListenerContainerTests implements PulsarTestContainerS
 				pulsarConsumerFactory, pulsarContainerProperties);
 		container.start();
 
-		Map<String, Object> prodConfig = Collections.singletonMap("topicName", "dpmlct-016");
+		Map<String, Object> prodConfig = Collections.singletonMap("topicName", "dpmlct-017");
 		DefaultPulsarProducerFactory<Integer> pulsarProducerFactory = new DefaultPulsarProducerFactory<>(pulsarClient,
 				prodConfig);
 		PulsarTemplate<Integer> pulsarTemplate = new PulsarTemplate<>(pulsarProducerFactory);