GH-3506: No array for poller messaging anns attr

Fixes https://github.com/spring-projects/spring-integration/issues/3506

Revise the `@Poller` usage in the messaging annotations from an array value
to a single entry with a `ValueConstants.DEFAULT_NONE` for default value

Code review feedback

- Make annotation utils check for NONE more generic
- Move docs to whats-new.adoc
- Polish javadoc

Code review feedback
- simplify docs
- simplify isProvided checks

spring-integration-core/src/main/java/org/springframework/integration/annotation/Aggregator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -34,6 +34,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
  * @author Marius Bogoevici
  * @author Oleg Zhurakousky
  * @author Artem Bilan
+ * @author Chris Bono
  */
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
@@ -105,10 +106,9 @@ public @interface Aggregator {
 	/**
 	 * @return the {@link Poller} options for a polled endpoint
 	 * ({@link org.springframework.integration.scheduling.PollerMetadata}).
-	 * This attribute is an {@code array} just to allow an empty default (no poller).
 	 * Mutually exclusive with {@link #reactive()}.
 	 */
-	Poller[] poller() default { };
+	Poller poller() default @Poller(ValueConstants.DEFAULT_NONE);
 
 	/**
 	 * @return the {@link Reactive} marker for a consumer endpoint.

spring-integration-core/src/main/java/org/springframework/integration/annotation/BridgeFrom.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 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.
@@ -38,6 +38,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
  * is used as the {@code outputChannel} of the {@link org.springframework.integration.handler.BridgeHandler}.
  *
  * @author Artem Bilan
+ * @author Chris Bono
  *
  * @since 4.0
  */
@@ -70,10 +71,9 @@ public @interface BridgeFrom {
 	/**
 	 * @return the {@link Poller} options for a polled endpoint
 	 * ({@link org.springframework.integration.scheduling.PollerMetadata}).
-	 * This attribute is an {@code array} just to allow an empty default (no poller).
 	 * Mutually exclusive with {@link #reactive()}.
 	 */
-	Poller[] poller() default { };
+	Poller poller() default @Poller(ValueConstants.DEFAULT_NONE);
 
 	/**
 	 * @return the {@link Reactive} marker for a consumer endpoint.

spring-integration-core/src/main/java/org/springframework/integration/annotation/BridgeTo.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 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.
@@ -43,6 +43,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
  * If no output channel is provided and no reply-channel exists, an exception is thrown.
  *
  * @author Artem Bilan
+ * @author Chris Bono
  *
  * @since 4.0
  */
@@ -77,10 +78,9 @@ public @interface BridgeTo {
 	/**
 	 * @return the {@link Poller} options for a polled endpoint
 	 * ({@link org.springframework.integration.scheduling.PollerMetadata}).
-	 * This attribute is an {@code array} just to allow an empty default (no poller).
 	 * Mutually exclusive with {@link #reactive()}.
 	 */
-	Poller[] poller() default { };
+	Poller poller() default @Poller(ValueConstants.DEFAULT_NONE);
 
 	/**
 	 * @return the {@link Reactive} marker for a consumer endpoint.

spring-integration-core/src/main/java/org/springframework/integration/annotation/Filter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -40,6 +40,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
  * @author Mark Fisher
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Chris Bono
  *
  * @since 2.0
  */
@@ -128,10 +129,9 @@ public @interface Filter {
 	/**
 	 * @return the {@link Poller} options for a polled endpoint
 	 * ({@link org.springframework.integration.scheduling.PollerMetadata}).
-	 * This attribute is an {@code array} just to allow an empty default (no poller).
 	 * Mutually exclusive with {@link #reactive()}.
 	 */
-	Poller[] poller() default { };
+	Poller poller() default @Poller(ValueConstants.DEFAULT_NONE);
 
 	/**
 	 * @return the {@link Reactive} marker for a consumer endpoint.

spring-integration-core/src/main/java/org/springframework/integration/annotation/InboundChannelAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2022 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.
@@ -23,6 +23,7 @@ import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
 import org.springframework.core.annotation.AliasFor;
+import org.springframework.messaging.handler.annotation.ValueConstants;
 
 /**
  * Indicates that a method is capable of producing a {@link org.springframework.messaging.Message}
@@ -45,6 +46,7 @@ import org.springframework.core.annotation.AliasFor;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Chris Bono
  *
  * @since 4.0
  */
@@ -86,10 +88,8 @@ public @interface InboundChannelAdapter {
 	/**
 	 * @return the {@link org.springframework.integration.annotation.Poller} options for a polled endpoint
 	 * ({@link org.springframework.integration.scheduling.PollerMetadata}).
-	 * This attribute is an {@code array} just to allow an empty default (no poller).
-	 * Only one {@link org.springframework.integration.annotation.Poller} element is allowed.
 	 * NOTE: a {@link Poller} here has {@link Poller#maxMessagesPerPoll()} set to 1 by default.
 	 */
-	Poller[] poller() default { };
+	Poller poller() default @Poller(ValueConstants.DEFAULT_NONE);
 
 }

spring-integration-core/src/main/java/org/springframework/integration/annotation/Router.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -45,6 +45,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
  *
  * @author Mark Fisher
  * @author Artem Bilan
+ * @author Chris Bono
  */
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
@@ -151,10 +152,9 @@ public @interface Router {
 	/**
 	 * @return the {@link Poller} options for a polled endpoint
 	 * ({@link org.springframework.integration.scheduling.PollerMetadata}).
-	 * This attribute is an {@code array} just to allow an empty default (no poller).
 	 * Mutually exclusive with {@link #reactive()}.
 	 */
-	Poller[] poller() default { };
+	Poller poller() default @Poller(ValueConstants.DEFAULT_NONE);
 
 	/**
 	 * @return the {@link Reactive} marker for a consumer endpoint.

spring-integration-core/src/main/java/org/springframework/integration/annotation/ServiceActivator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -43,6 +43,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
  * @author Gary Russell
  * @author Artem Bilan
  * @author Yilin Wei
+ * @author Chris Bono
  */
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
@@ -121,11 +122,9 @@ public @interface ServiceActivator {
 	/**
 	 * @return the {@link Poller} options for a polled endpoint
 	 * ({@link org.springframework.integration.scheduling.PollerMetadata}).
-	 * This attribute is an {@code array} just to allow an empty default (no poller).
-	 * Only one {@link Poller} element is allowed.
 	 * Mutually exclusive with {@link #reactive()}.
 	 */
-	Poller[] poller() default { };
+	Poller poller() default @Poller(ValueConstants.DEFAULT_NONE);
 
 	/**
 	 * @return the {@link Reactive} marker for a consumer endpoint.

spring-integration-core/src/main/java/org/springframework/integration/annotation/Splitter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -43,6 +43,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
  * @author Mark Fisher
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Chris Bono
  */
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
@@ -116,10 +117,9 @@ public @interface Splitter {
 	/**
 	 * @return the {@link Poller} options for a polled endpoint
 	 * ({@link org.springframework.integration.scheduling.PollerMetadata}).
-	 * This attribute is an {@code array} just to allow an empty default (no poller).
 	 * Mutually exclusive with {@link #reactive()}.
 	 */
-	Poller[] poller() default { };
+	Poller poller() default @Poller(ValueConstants.DEFAULT_NONE);
 
 	/**
 	 * @return the {@link Reactive} marker for a consumer endpoint.

spring-integration-core/src/main/java/org/springframework/integration/annotation/Transformer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -31,6 +31,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
  * @author Mark Fisher
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Chris Bono
  */
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
@@ -92,10 +93,9 @@ public @interface Transformer {
 	/**
 	 * @return the {@link Poller} options for a polled endpoint
 	 * ({@link org.springframework.integration.scheduling.PollerMetadata}).
-	 * This attribute is an {@code array} just to allow an empty default (no poller).
 	 * Mutually exclusive with {@link #reactive()}.
 	 */
-	Poller[] poller() default { };
+	Poller poller() default @Poller(ValueConstants.DEFAULT_NONE);
 
 	/**
 	 * @return the {@link Reactive} marker for a consumer endpoint.

spring-integration-core/src/main/java/org/springframework/integration/config/annotation/AbstractMethodAnnotationPostProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -84,7 +84,6 @@ import org.springframework.messaging.PollableChannel;
 import org.springframework.messaging.SubscribableChannel;
 import org.springframework.messaging.core.DestinationResolutionException;
 import org.springframework.messaging.core.DestinationResolver;
-import org.springframework.messaging.handler.annotation.ValueConstants;
 import org.springframework.scheduling.Trigger;
 import org.springframework.scheduling.support.CronTrigger;
 import org.springframework.scheduling.support.PeriodicTrigger;
@@ -103,6 +102,7 @@ import reactor.core.publisher.Flux;
  * @author Mark Fisher
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Chris Bono
  */
 public abstract class AbstractMethodAnnotationPostProcessor<T extends Annotation>
 		implements MethodAnnotationPostProcessor<T> {
@@ -363,24 +363,24 @@ public abstract class AbstractMethodAnnotationPostProcessor<T extends Annotation
 	protected AbstractEndpoint doCreateEndpoint(MessageHandler handler, MessageChannel inputChannel,
 			List<Annotation> annotations) {
 
-		Poller[] pollers = MessagingAnnotationUtils.resolveAttribute(annotations, "poller", Poller[].class);
+		Poller poller = MessagingAnnotationUtils.resolveAttribute(annotations, "poller", Poller.class);
-		Reactive reactive = MessagingAnnotationUtils.resolveAttribute(annotations, "reactive", Reactive.class);
-		boolean reactiveProvided = reactive != null && !ValueConstants.DEFAULT_NONE.equals(reactive.value());
 
-		Assert.state(!reactiveProvided || ObjectUtils.isEmpty(pollers),
+		Reactive reactive = MessagingAnnotationUtils.resolveAttribute(annotations, "reactive", Reactive.class);
+
+		Assert.state(reactive == null || poller == null,
 				"The 'poller' and 'reactive' are mutually exclusive.");
 
-		if (inputChannel instanceof Publisher || handler instanceof ReactiveMessageHandlerAdapter || reactiveProvided) {
+		if (inputChannel instanceof Publisher || handler instanceof ReactiveMessageHandlerAdapter || reactive != null) {
-			return reactiveStreamsConsumer(inputChannel, handler, reactiveProvided ? reactive : null);
+			return reactiveStreamsConsumer(inputChannel, handler, reactive);
 		}
 		else if (inputChannel instanceof SubscribableChannel) {
-			Assert.state(ObjectUtils.isEmpty(pollers), () ->
+			Assert.state(poller == null, () ->
 					"A '@Poller' should not be specified for Annotation-based " +
 							"endpoint, since '" + inputChannel + "' is a SubscribableChannel (not pollable).");
 			return new EventDrivenConsumer((SubscribableChannel) inputChannel, handler);
 		}
 		else if (inputChannel instanceof PollableChannel) {
-			return pollingConsumer(inputChannel, handler, pollers);
+			return pollingConsumer(inputChannel, handler, poller);
 		}
 		else {
 			throw new IllegalArgumentException("Unsupported 'inputChannel' type: '"
@@ -414,19 +414,15 @@ public abstract class AbstractMethodAnnotationPostProcessor<T extends Annotation
 		return reactiveStreamsConsumer;
 	}
 
-	private PollingConsumer pollingConsumer(MessageChannel inputChannel, MessageHandler handler, Poller[] pollers) {
+	private PollingConsumer pollingConsumer(MessageChannel inputChannel, MessageHandler handler, Poller poller) {
 		PollingConsumer pollingConsumer = new PollingConsumer((PollableChannel) inputChannel, handler);
-		configurePollingEndpoint(pollingConsumer, pollers);
+		configurePollingEndpoint(pollingConsumer, poller);
 		return pollingConsumer;
 	}
 
-	protected void configurePollingEndpoint(AbstractPollingEndpoint pollingEndpoint, Poller[] pollers) {
+	protected void configurePollingEndpoint(AbstractPollingEndpoint pollingEndpoint, Poller poller) {
 		PollerMetadata pollerMetadata;
-		if (!ObjectUtils.isEmpty(pollers)) {
+		if (poller != null) {
-			Assert.state(pollers.length == 1,
-					"The 'poller' for an Annotation-based endpoint can have only one '@Poller'.");
-			Poller poller = pollers[0];
-
 			String ref = poller.value();
 			String triggerRef = poller.trigger();
 			String executorRef = poller.taskExecutor();

spring-integration-core/src/main/java/org/springframework/integration/config/annotation/InboundChannelAdapterAnnotationPostProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 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.
@@ -44,6 +44,7 @@ import org.springframework.util.Assert;
  * @author Artem Bilan
  * @author Gary Russell
  * @author Oleg Zhurakousky
+ * @author Chris Bono
  *
  * @since 4.0
  */
@@ -82,8 +83,8 @@ public class InboundChannelAdapterAnnotationPostProcessor extends
 		SourcePollingChannelAdapter adapter = new SourcePollingChannelAdapter();
 		adapter.setOutputChannelName(channelName);
 		adapter.setSource(messageSource);
-		Poller[] pollers = MessagingAnnotationUtils.resolveAttribute(annotations, "poller", Poller[].class);
+		Poller poller = MessagingAnnotationUtils.resolveAttribute(annotations, "poller", Poller.class);
-		configurePollingEndpoint(adapter, pollers);
+		configurePollingEndpoint(adapter, poller);
 
 		return adapter;
 	}

spring-integration-core/src/main/java/org/springframework/integration/util/MessagingAnnotationUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 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.
@@ -30,8 +30,9 @@ import org.springframework.messaging.MessagingException;
 import org.springframework.messaging.handler.annotation.Header;
 import org.springframework.messaging.handler.annotation.Headers;
 import org.springframework.messaging.handler.annotation.Payload;
+import org.springframework.messaging.handler.annotation.ValueConstants;
+import org.springframework.util.ObjectUtils;
 import org.springframework.util.ReflectionUtils;
-import org.springframework.util.StringUtils;
 
 /**
  * Utility methods to support annotation processing.
@@ -41,17 +42,16 @@ import org.springframework.util.StringUtils;
  * @author Gunnar Hillert
  * @author Soby Chacko
  * @author Artem Bilan
+ * @author Chris Bono
  *
  * @since 4.0
  */
 public final class MessagingAnnotationUtils {
 
 	/**
-	 * Get the attribute value from the annotation hierarchy, returning the first non-empty
+	 * Get the attribute value from the annotation hierarchy, returning the first
-	 * value closest to the annotated method. While traversing up the hierarchy, for string-valued
+	 * {@link MessagingAnnotationUtils#hasValue non-empty}) value closest to the annotated method.
-	 * attributes, an empty string is ignored. For array-valued attributes, an empty
+	 *
-	 * array is ignored.
-	 * The overridden attribute must be the same type.
 	 * @param annotations The meta-annotations in order (closest first).
 	 * @param name The attribute name.
 	 * @param requiredType The expected type.
@@ -69,9 +69,30 @@ public final class MessagingAnnotationUtils {
 		return null;
 	}
 
-	public static boolean hasValue(Object value) {
+	/**
-		return value != null && (!(value instanceof String) || (StringUtils.hasText((String) value))) // NOSONAR
+	 * Determine if the value of a named attribute from an annotation instance contains an actual value.
-				&& (!value.getClass().isArray() || ((Object[]) value).length > 0);
+	 * @param annotationValue the value of the annotation attribute
+	 * @return {@code false} when {@code annotationValue} is null, an empty string, an empty array, or any annotation
+	 * whose 'value' field is set to {@link ValueConstants#DEFAULT_NONE} - {@code true} otherwise
+	 */
+	public static boolean hasValue(Object annotationValue) {
+		if (annotationValue == null) {
+			return false;
+		}
+		// Empty array
+		if (ObjectUtils.isArray(annotationValue) && ObjectUtils.isEmpty(annotationValue)) {
+			return false;
+		}
+		// Empty string
+		if ((annotationValue instanceof String) && ObjectUtils.isEmpty(annotationValue)) {
+			return false;
+		}
+		// Annotation with 'value' set to special 'none' string
+		if ((annotationValue instanceof Annotation) &&
+				ValueConstants.DEFAULT_NONE.equals(AnnotationUtils.getValue((Annotation) annotationValue))) {
+			return false;
+		}
+		return true;
 	}
 
 	public static Method findAnnotatedMethod(Object target, final Class<? extends Annotation> annotationType) {

spring-integration-core/src/test/java/org/springframework/integration/configuration/EnableIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 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.
@@ -127,6 +127,7 @@ import org.springframework.messaging.MessageDeliveryException;
 import org.springframework.messaging.MessageHandler;
 import org.springframework.messaging.PollableChannel;
 import org.springframework.messaging.handler.annotation.Payload;
+import org.springframework.messaging.handler.annotation.ValueConstants;
 import org.springframework.messaging.support.ChannelInterceptor;
 import org.springframework.messaging.support.GenericMessage;
 import org.springframework.scheduling.Trigger;
@@ -148,6 +149,7 @@ import reactor.core.publisher.Mono;
  * @author Artem Bilan
  * @author Gary Russell
  * @author Michael Wiles
+ * @author Chris Bono
  *
  * @since 4.0
  */
@@ -1506,7 +1508,7 @@ public class EnableIntegrationTests {
 
 		String phase() default "";
 
-		Poller[] poller() default { };
+		Poller poller() default @Poller(ValueConstants.DEFAULT_NONE);
 
 	}
 
@@ -1525,7 +1527,7 @@ public class EnableIntegrationTests {
 
 		String phase() default "";
 
-		Poller[] poller() default { };
+		Poller poller() default @Poller(ValueConstants.DEFAULT_NONE);
 
 	}
 
@@ -1631,7 +1633,7 @@ public class EnableIntegrationTests {
 
 		String phase() default "";
 
-		Poller[] poller() default { };
+		Poller poller() default @Poller(ValueConstants.DEFAULT_NONE);
 
 	}
 
@@ -1664,7 +1666,7 @@ public class EnableIntegrationTests {
 
 		String phase() default "";
 
-		Poller[] poller() default { };
+		Poller poller() default @Poller(ValueConstants.DEFAULT_NONE);
 
 	}
 

spring-integration-core/src/test/kotlin/org/springframework/integration/function/FunctionsTests.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2021 the original author or authors.
+ * Copyright 2018-2022 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.
@@ -56,6 +56,7 @@ import java.util.stream.Collectors
 
 /**
  * @author Artem Bilan
+ * @author Chris Bono
  *
  * @since 5.1
  */
@@ -171,7 +172,7 @@ class FunctionsTests {
 
 		@Bean
 		@InboundChannelAdapter(value = "counterChannel", autoStartup = "false",
-				poller = [Poller(fixedRate = "10", maxMessagesPerPoll = "1")])
+				poller = Poller(fixedRate = "10", maxMessagesPerPoll = "1"))
 		@EndpointId("kotlinSupplierChannelAdapter")
 		fun kotlinSupplier(): () -> String {
 			return { "baz" }

src/reference/asciidoc/whats-new.adoc

@@ -26,6 +26,9 @@ See <<./graphql.adoc#graphql,GraphQL Support>> for more information.
 [[x6.0-general]]
 === General Changes
 
+The messaging annotations don't require a poller attribute as an array of @Poller any more.
+See <<./configuration.adoc#configuration-using-poller-annotation,Using the @Poller Annotation>> for more information.
+
 [[x6.0-http]]
 === HTTP Changes
 
@@ -36,4 +39,4 @@ See <<./http.adoc#http,HTTP Support>> for more information.
 === RMI Removal
 
 The `spring-integration-rmi` module has been removed altogether after being deprecated in previous versions.
-There is no replacement: it is recommended to migrate to more secure network and application protocols, such as WebSockets, RSockets, gRPC or REST.
+There is no replacement: it is recommended to migrate to more secure network and application protocols, such as WebSockets, RSockets, gRPC or REST.