GH-9617: @SuppressWarnings("removal") for ListenableFuture

Fixes: #9617
Issue link: https://github.com/spring-projects/spring-integration/issues/9617

The `ListenableFuture` is marked `forRemoval` in Spring Framework.
So, fix the code base to use `@SuppressWarnings("removal")`.
Also, add a warning into logs that `ListenableFuture` support will be removed in `7.0`.

* Fix JavaDocs where `ListenableFuture` is mentioned in favor of `CompletableFuture`

build.gradle

@@ -114,7 +114,7 @@ ext {
     springKafkaVersion = '3.3.0-SNAPSHOT'
     springRetryVersion = '2.0.10'
     springSecurityVersion = '6.4.0-SNAPSHOT'
-    springVersion = '6.2.0-RC2'
+    springVersion = '6.2.0-SNAPSHOT'
     springWsVersion = '4.0.11'
     testcontainersVersion = '1.20.3'
     tomcatVersion = '10.1.31'

spring-integration-core/src/main/java/org/springframework/integration/gateway/GatewayProxyFactoryBean.java

@@ -363,9 +363,9 @@ public class GatewayProxyFactoryBean<T> extends AbstractEndpoint
 
 	/**
 	 * Set the executor for use when the gateway method returns
-	 * {@link java.util.concurrent.Future} or {@link org.springframework.util.concurrent.ListenableFuture}.
+	 * {@link Future} or {@link CompletableFuture}.
 	 * Set it to null to disable the async processing, and any
-	 * {@link java.util.concurrent.Future} return types must be returned by the downstream flow.
+	 * {@link Future} return types must be returned by the downstream flow.
 	 * @param executor The executor.
 	 */
 	public void setAsyncExecutor(@Nullable Executor executor) {
@@ -522,7 +522,7 @@ public class GatewayProxyFactoryBean<T> extends AbstractEndpoint
 
 	@Override
 	@Nullable
-	@SuppressWarnings("deprecation")
+	@SuppressWarnings("removal")
 	public Object invoke(final MethodInvocation invocation) throws Throwable { // NOSONAR
 		Method method = invocation.getMethod();
 		Class<?> returnType;
@@ -542,6 +542,9 @@ public class GatewayProxyFactoryBean<T> extends AbstractEndpoint
 				return CompletableFuture.supplyAsync(invoker, this.asyncExecutor);
 			}
 			else if (org.springframework.util.concurrent.ListenableFuture.class.equals(returnType)) {
+				logger.warn("The 'org.springframework.util.concurrent.ListenableFuture' is deprecated for removal." +
+						"The 'CompletableFuture' is recommended to be used instead." +
+						"The 'ListenableFuture' support will be removed in Spring Integration 7.0.");
 				return ((org.springframework.core.task.AsyncListenableTaskExecutor) this.asyncExecutor)
 						.submitListenable(invoker::get);
 			}

spring-integration-core/src/main/java/org/springframework/integration/handler/AbstractMessageProducingHandler.java

@@ -71,7 +71,7 @@ import org.springframework.util.StringUtils;
  * @author Marius Bogoevici
  * @author Ngoc Nhan
  *
- * since 4.1
+ * @since 4.1
  */
 public abstract class AbstractMessageProducingHandler extends AbstractMessageHandler
 		implements MessageProducer, HeaderPropagationAware {
@@ -321,7 +321,7 @@ public abstract class AbstractMessageProducingHandler extends AbstractMessageHan
 		return replyChannel;
 	}
 
-	@SuppressWarnings("deprecation")
+	@SuppressWarnings("removal")
 	private void doProduceOutput(Message<?> requestMessage, MessageHeaders requestHeaders, Object reply,
 			@Nullable Object replyChannelArg) {
 
@@ -361,7 +361,7 @@ public abstract class AbstractMessageProducingHandler extends AbstractMessageHan
 		sendOutput(createOutputMessage(reply, requestHeaders), replyChannel, false);
 	}
 
-	private static Publisher<?> toPublisherReply(Object reply, @Nullable ReactiveAdapter reactiveAdapter) {
+	private Publisher<?> toPublisherReply(Object reply, @Nullable ReactiveAdapter reactiveAdapter) {
 		if (reactiveAdapter != null) {
 			return reactiveAdapter.toPublisher(reply);
 		}
@@ -371,7 +371,7 @@ public abstract class AbstractMessageProducingHandler extends AbstractMessageHan
 	}
 
 	@SuppressWarnings("try")
-	private static CompletableFuture<?> toFutureReply(Object reply, @Nullable ReactiveAdapter reactiveAdapter) {
+	private CompletableFuture<?> toFutureReply(Object reply, @Nullable ReactiveAdapter reactiveAdapter) {
 		if (reactiveAdapter != null) {
 			Mono<?> reactiveReply;
 			Publisher<?> publisher = reactiveAdapter.toPublisher(reply);
@@ -419,12 +419,15 @@ public abstract class AbstractMessageProducingHandler extends AbstractMessageHan
 		}
 	}
 
-	@SuppressWarnings("deprecation")
-	private static CompletableFuture<?> toCompletableFuture(Object reply) {
-		if (reply instanceof CompletableFuture<?>) {
-			return (CompletableFuture<?>) reply;
+	@SuppressWarnings("removal")
+	private CompletableFuture<?> toCompletableFuture(Object reply) {
+		if (reply instanceof CompletableFuture<?> completableFuture) {
+			return completableFuture;
 		}
 		else {
+			logger.warn("The 'org.springframework.util.concurrent.ListenableFuture' is deprecated for removal." +
+					"The 'CompletableFuture' is recommended to be used instead." +
+					"The 'ListenableFuture' support will be removed in Spring Integration 7.0.");
 			return ((org.springframework.util.concurrent.ListenableFuture<?>) reply).completable();
 		}
 	}

spring-integration-core/src/test/java/org/springframework/integration/gateway/GatewayInterfaceTests.java

@@ -444,14 +444,6 @@ public class GatewayInterfaceTests {
 		assertThat(latch.await(10, TimeUnit.SECONDS)).isTrue();
 		assertThat(result2.get().getName()).startsWith("exec-");
 
-		org.springframework.util.concurrent.ListenableFuture<Thread> result3 =
-				this.execGateway.test3(Thread.currentThread());
-		final CountDownLatch latch1 = new CountDownLatch(1);
-		result3.addCallback(data -> latch1.countDown(), ex -> {
-		});
-		assertThat(latch1.await(10, TimeUnit.SECONDS)).isTrue();
-		assertThat(result3.get().getName()).startsWith("exec-");
-
 		/*
 		@IntegrationComponentScan(useDefaultFilters = false,
 		includeFilters = @ComponentScan.Filter(TestMessagingGateway.class))
@@ -770,10 +762,6 @@ public class GatewayInterfaceTests {
 		@Gateway(requestChannel = "gatewayThreadChannel")
 		CompletableFuture<Thread> test2(Thread caller);
 
-		@Gateway(requestChannel = "gatewayThreadChannel")
-		@SuppressWarnings("deprecation")
-		org.springframework.util.concurrent.ListenableFuture<Thread> test3(Thread caller);
-
 	}
 
 	@MessagingGateway(name = "noExecutorGateway", asyncExecutor = AnnotationConstants.NULL)

spring-integration-rsocket/src/main/java/org/springframework/integration/rsocket/outbound/RSocketOutboundGateway.java

@@ -50,18 +50,18 @@ import org.springframework.util.MimeType;
  * <p>
  * An RSocket operation is determined by the configured {@link RSocketInteractionModel} or respective SpEL
  * expression to be evaluated at runtime against the request message.
- * By default the {@link RSocketInteractionModel#requestResponse} operation is used.
+ * By default, the {@link RSocketInteractionModel#requestResponse} operation is used.
  * <p>
  * For a {@link Publisher}-based requests, it must be present in the request message {@code payload}.
  * The flattening via upstream {@link org.springframework.integration.channel.FluxMessageChannel} will work, too,
  * but this way we will lose a scope of particular request and every {@link Publisher} event
- * will be send in its own plain request.
+ * will be sent in its own plain request.
  * <p>
  * If reply is a {@link reactor.core.publisher.Flux}, it is wrapped to the {@link Mono} to retain a request scope.
  * The downstream flow is responsible to obtain this {@link reactor.core.publisher.Flux} from a message payload
  * and subscribe to it by itself. The {@link Mono} reply from this component is subscribed from the downstream
  * {@link org.springframework.integration.channel.FluxMessageChannel} or it is adapted to the
- * {@link org.springframework.util.concurrent.ListenableFuture} otherwise.
+ * {@link java.util.concurrent.CompletableFuture} otherwise.
  *
  * @author Artem Bilan
  *

spring-integration-stomp/src/main/java/org/springframework/integration/stomp/AbstractStompSessionManager.java

@@ -49,11 +49,10 @@ import org.springframework.messaging.simp.stomp.StompSessionHandlerAdapter;
 import org.springframework.scheduling.TaskScheduler;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
-import org.springframework.util.concurrent.ListenableFuture;
 
 /**
  * Base {@link StompSessionManager} implementation to manage a single {@link StompSession}
- * over its {@link ListenableFuture} from the target implementation of this class.
+ * over its {@link CompletableFuture} from the target implementation of this class.
  * <p>
  * The connection to the {@link StompSession} is made during {@link #start()}.
  * <p>

src/reference/antora/modules/ROOT/pages/gateway.adoc

@@ -618,9 +618,6 @@ There are two modes of operation when returning this type:
 * When the async executor is explicitly set to `null` and the return type is `CompletableFuture` or the return type is a subclass of `CompletableFuture`, the flow is invoked on the caller's thread.
 In this scenario, the downstream flow is expected to return a `CompletableFuture` of the appropriate type.
 
-NOTE: The `org.springframework.util.concurrent.ListenableFuture` has been deprecated starting with Spring Framework `6.0`.
-It is recommended now to migrate to the `CompletableFuture` which provides similar processing functionality.
-
 [[usage-scenarios]]
 ==== Usage Scenarios