GH-2708: Make messaging annotations as repeatable

Fixes https://github.com/spring-projects/spring-integration/issues/2708

There are some requests to use the same service method for different input channels

* Make all the messaging annotations as `@Repeatable` with their
respective container annotations
* Modify `MessagingAnnotationPostProcessor` logic to deal with the mentioned repeatable
requirements

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

@@ -18,6 +18,7 @@ package org.springframework.integration.annotation;
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
@@ -39,6 +40,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
+@Repeatable(Aggregators.class)
 public @interface Aggregator {
 
 	/**

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * The repeatable container for {@link Aggregator} annotations.
+ *
+ * @author Artem Bilan
+ *
+ * @since 6.0
+ */
+@Documented
+@Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Aggregators {
+
+	Aggregator[] value();
+
+}

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

@@ -18,6 +18,7 @@ package org.springframework.integration.annotation;
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
@@ -45,6 +46,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
+@Repeatable(BridgeFromRepeatable.class)
 public @interface BridgeFrom {
 
 	/**

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * The repeatable container for {@link BridgeFrom} annotations.
+ *
+ * @author Artem Bilan
+ *
+ * @since 6.0
+ */
+@Documented
+@Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface BridgeFromRepeatable {
+
+	BridgeFrom[] value();
+
+}

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

@@ -18,6 +18,7 @@ package org.springframework.integration.annotation;
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
@@ -50,6 +51,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
+@Repeatable(BridgeToRepeatable.class)
 public @interface BridgeTo {
 
 	/**

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * The repeatable container for {@link BridgeTo} annotations.
+ *
+ * @author Artem Bilan
+ *
+ * @since 6.0
+ */
+@Documented
+@Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface BridgeToRepeatable {
+
+	BridgeTo[] value();
+
+}

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

@@ -18,6 +18,7 @@ package org.springframework.integration.annotation;
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
@@ -47,6 +48,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
+@Repeatable(Filters.class)
 public @interface Filter {
 
 	/**

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * The repeatable container for {@link Filter} annotations.
+ *
+ * @author Artem Bilan
+ *
+ * @since 6.0
+ */
+@Documented
+@Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Filters {
+
+	Filter[] value();
+
+}

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

@@ -18,6 +18,7 @@ package org.springframework.integration.annotation;
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
@@ -53,6 +54,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
+@Repeatable(InboundChannelAdapters.class)
 public @interface InboundChannelAdapter {
 
 	/**

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * The repeatable container for {@link InboundChannelAdapter} annotations.
+ *
+ * @author Artem Bilan
+ *
+ * @since 6.0
+ */
+@Documented
+@Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface InboundChannelAdapters {
+
+	InboundChannelAdapter[] value();
+
+}

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

@@ -18,6 +18,7 @@ package org.springframework.integration.annotation;
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
@@ -50,6 +51,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
+@Repeatable(Routers.class)
 public @interface Router {
 
 	/**

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * The repeatable container for {@link Router} annotations.
+ *
+ * @author Artem Bilan
+ *
+ * @since 6.0
+ */
+@Documented
+@Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Routers {
+
+	Router[] value();
+
+}

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

@@ -18,6 +18,7 @@ package org.springframework.integration.annotation;
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
@@ -48,6 +49,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
+@Repeatable(ServiceActivators.class)
 public @interface ServiceActivator {
 
 	/**

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * The repeatable container for {@link ServiceActivator} annotations.
+ *
+ * @author Artem Bilan
+ *
+ * @since 6.0
+ */
+@Documented
+@Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface ServiceActivators {
+
+	ServiceActivator[] value();
+
+}

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

@@ -18,6 +18,7 @@ package org.springframework.integration.annotation;
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
@@ -48,6 +49,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
+@Repeatable(Splitters.class)
 public @interface Splitter {
 
 	/**

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * The repeatable container for {@link Splitter} annotations.
+ *
+ * @author Artem Bilan
+ *
+ * @since 6.0
+ */
+@Documented
+@Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Splitters {
+
+	Splitter[] value();
+
+}

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

@@ -18,6 +18,7 @@ package org.springframework.integration.annotation;
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
@@ -36,6 +37,7 @@ import org.springframework.messaging.handler.annotation.ValueConstants;
 @Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
+@Repeatable(Transformers.class)
 public @interface Transformer {
 
 	/**

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * The repeatable container for {@link Transformer} annotations.
+ *
+ * @author Artem Bilan
+ *
+ * @since 6.0
+ */
+@Documented
+@Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Transformers {
+
+	Transformer[] value();
+
+}

spring-integration-core/src/main/java/org/springframework/integration/config/annotation/MessagingAnnotationPostProcessor.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.
@@ -25,7 +25,6 @@ import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
-import java.util.Map.Entry;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
@@ -42,13 +41,13 @@ import org.springframework.beans.factory.config.BeanPostProcessor;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.RootBeanDefinition;
-import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.annotation.MergedAnnotation;
 import org.springframework.core.annotation.MergedAnnotations;
 import org.springframework.integration.annotation.Aggregator;
 import org.springframework.integration.annotation.BridgeFrom;
 import org.springframework.integration.annotation.BridgeTo;
+import org.springframework.integration.annotation.EndpointId;
 import org.springframework.integration.annotation.Filter;
 import org.springframework.integration.annotation.InboundChannelAdapter;
 import org.springframework.integration.annotation.Role;
@@ -161,28 +160,34 @@ public class MessagingAnnotationPostProcessor implements BeanPostProcessor, Bean
 	}
 
 	private void doWithMethod(Method method, Object bean, String beanName, Class<?> beanClass) {
-		Map<Class<? extends Annotation>, List<Annotation>> annotationChains = new HashMap<>();
-		for (Class<? extends Annotation> annotationType :
-				this.postProcessors.keySet()) {
-			if (AnnotatedElementUtils.isAnnotated(method, annotationType.getName())) {
-				List<Annotation> annotationChain = getAnnotationChain(method, annotationType);
-				if (annotationChain.size() > 0) {
-					annotationChains.put(annotationType, annotationChain);
-				}
-			}
+		MergedAnnotations mergedAnnotations =
+				MergedAnnotations.search(MergedAnnotations.SearchStrategy.DIRECT)
+						.from(method);
+
+		List<MessagingMetaAnnotation> messagingAnnotations = new ArrayList<>();
+
+		for (Class<? extends Annotation> annotationType : this.postProcessors.keySet()) {
+			mergedAnnotations.stream()
+					.filter((ann) -> ann.getType().equals(annotationType))
+					.map(MergedAnnotation::getRoot)
+					.map(MergedAnnotation::synthesize)
+					.map((ann) -> new MessagingMetaAnnotation(ann, annotationType))
+					.forEach(messagingAnnotations::add);
 		}
-		if (StringUtils.hasText(MessagingAnnotationUtils.endpointIdValue(method))
-				&& annotationChains.keySet().size() > 1) {
+		if (mergedAnnotations.get(EndpointId.class, (ann) -> ann.hasNonDefaultValue("value")).isPresent()
+				&& messagingAnnotations.size() > 1) {
+
 			throw new IllegalStateException("@EndpointId on " + method.toGenericString()
-					+ " can only have one EIP annotation, found: " + annotationChains.keySet().size());
-		}
-		for (Entry<Class<? extends Annotation>, List<Annotation>> entry : annotationChains.entrySet()) {
-			Class<? extends Annotation> annotationType = entry.getKey();
-			List<Annotation> annotations = entry.getValue();
-			processAnnotationTypeOnMethod(bean, beanName, method, annotationType, annotations);
+					+ " can only have one EIP annotation, found: " + messagingAnnotations.size());
 		}
 
-		if (annotationChains.size() == 0) {
+		for (MessagingMetaAnnotation messagingAnnotation : messagingAnnotations) {
+			Class<? extends Annotation> annotationType = messagingAnnotation.messagingAnnotationType;
+			List<Annotation> annotationChain = getAnnotationChain(messagingAnnotation.annotation, annotationType);
+			processAnnotationTypeOnMethod(bean, beanName, method, annotationType, annotationChain);
+		}
+
+		if (messagingAnnotations.size() == 0) {
 			this.noAnnotationsCache.add(beanClass);
 		}
 	}
@@ -226,10 +231,8 @@ public class MessagingAnnotationPostProcessor implements BeanPostProcessor, Bean
 		Object result = postProcessor.postProcess(bean, beanName, targetMethod, annotations);
 		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
 		BeanDefinitionRegistry definitionRegistry = (BeanDefinitionRegistry) beanFactory;
-		if (result instanceof AbstractEndpoint) {
-			AbstractEndpoint endpoint = (AbstractEndpoint) result;
-			String autoStartup = MessagingAnnotationUtils.resolveAttribute(annotations, "autoStartup",
-					String.class);
+		if (result instanceof AbstractEndpoint endpoint) {
+			String autoStartup = MessagingAnnotationUtils.resolveAttribute(annotations, "autoStartup", String.class);
 			if (StringUtils.hasText(autoStartup)) {
 				autoStartup = beanFactory.resolveEmbeddedValue(autoStartup);
 				if (StringUtils.hasText(autoStartup)) {
@@ -259,20 +262,19 @@ public class MessagingAnnotationPostProcessor implements BeanPostProcessor, Bean
 	}
 
 	/**
-	 * @param method         the method.
+	 * @param messagingAnnotation the {@link Annotation} to take a chain for its meta-annotations.
 	 * @param annotationType the annotation type.
 	 * @return the hierarchical list of annotations in top-bottom order.
 	 */
-	protected List<Annotation> getAnnotationChain(Method method, Class<? extends Annotation> annotationType) {
+	protected List<Annotation> getAnnotationChain(Annotation messagingAnnotation,
+			Class<? extends Annotation> annotationType) {
+
 		List<Annotation> annotationChain = new LinkedList<>();
 		Set<Annotation> visited = new HashSet<>();
 
-		for (MergedAnnotation<Annotation> mergedAnnotation : MergedAnnotations.from(method)) {
-			recursiveFindAnnotation(annotationType, mergedAnnotation.synthesize(), annotationChain, visited);
-			if (annotationChain.size() > 0) {
-				Collections.reverse(annotationChain);
-				return annotationChain;
-			}
+		recursiveFindAnnotation(annotationType, messagingAnnotation, annotationChain, visited);
+		if (annotationChain.size() > 0) {
+			Collections.reverse(annotationChain);
 		}
 
 		return annotationChain;
@@ -280,6 +282,7 @@ public class MessagingAnnotationPostProcessor implements BeanPostProcessor, Bean
 
 	protected boolean recursiveFindAnnotation(Class<? extends Annotation> annotationType, Annotation ann,
 			List<Annotation> annotationChain, Set<Annotation> visited) {
+
 		if (ann.annotationType().equals(annotationType)) {
 			annotationChain.add(ann);
 			return true;
@@ -299,6 +302,7 @@ public class MessagingAnnotationPostProcessor implements BeanPostProcessor, Bean
 
 	protected String generateBeanName(String originalBeanName, Method method,
 			Class<? extends Annotation> annotationType) {
+
 		String name = MessagingAnnotationUtils.endpointIdValue(method);
 		if (!StringUtils.hasText(name)) {
 			String baseName = originalBeanName + "." + method.getName() + "."
@@ -316,4 +320,8 @@ public class MessagingAnnotationPostProcessor implements BeanPostProcessor, Bean
 		return this.postProcessors;
 	}
 
+	private record MessagingMetaAnnotation(Annotation annotation, Class<? extends Annotation> messagingAnnotationType) {
+
+	}
+
 }

spring-integration-core/src/test/java/org/springframework/integration/config/annotation/MessagingAnnotationPostProcessorTests.java

@@ -298,6 +298,12 @@ public class MessagingAnnotationPostProcessorTests {
 		inputChannel.send(new GenericMessage<>("foo"));
 		Message<?> reply = outputChannel.receive(0);
 		assertThat(reply.getPayload()).isEqualTo("FOO");
+
+		MessageChannel inputChannel2 = context.getBean("inputChannel2", MessageChannel.class);
+		inputChannel2.send(new GenericMessage<>("test2"));
+		reply = outputChannel.receive(0);
+		assertThat(reply.getPayload()).isEqualTo("TEST2");
+
 		context.close();
 	}
 
@@ -386,6 +392,7 @@ public class MessagingAnnotationPostProcessorTests {
 	public static class TransformerAnnotationTestBean {
 
 		@Transformer(inputChannel = "inputChannel", outputChannel = "outputChannel")
+		@Transformer(inputChannel = "inputChannel2", outputChannel = "outputChannel")
 		public String transformBefore(String input) {
 			return input.toUpperCase();
 		}

spring-integration-core/src/test/java/org/springframework/integration/config/annotation/MessagingAnnotationsWithBeanAnnotationTests.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.
@@ -385,9 +385,9 @@ public class MessagingAnnotationsWithBeanAnnotationTests {
 
 		@Bean
 		@ServiceActivator(inputChannel = "skippedChannel")
-		@Splitter(inputChannel = "skippedChannel2")
+		@ServiceActivator(inputChannel = "skippedChannel2")
 		@Router(inputChannel = "skippedChannel3")
-		@Transformer(inputChannel = "skippedChannel4")
+		@Filter(inputChannel = "skippedChannel4")
 		@Filter(inputChannel = "skippedChannel5")
 		@Profile("foo")
 		public MessageHandler skippedMessageHandler() {
@@ -396,6 +396,7 @@ public class MessagingAnnotationsWithBeanAnnotationTests {
 		}
 
 		@Bean
+		@BridgeFrom("skippedChannel5")
 		@BridgeFrom("skippedChannel6")
 		@Profile("foo")
 		public MessageChannel skippedChannel1() {

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

@@ -250,6 +250,9 @@ public class EnableIntegrationTests {
 	@Autowired
 	private PollableChannel messageChannel;
 
+	@Autowired
+	private PollableChannel messageChannel2;
+
 	@Autowired
 	private PollableChannel fooChannel;
 
@@ -432,6 +435,12 @@ public class EnableIntegrationTests {
 		assertThat(message.getHeaders().containsKey("foo")).isTrue();
 		assertThat(message.getHeaders().get("foo")).isEqualTo("FOO");
 
+		message = this.messageChannel2.receive(10_000);
+		assertThat(message).isNotNull();
+		assertThat(message.getPayload()).isEqualTo("bar");
+		assertThat(message.getHeaders().containsKey("foo")).isTrue();
+		assertThat(message.getHeaders().get("foo")).isEqualTo("FOO");
+
 		MessagingTemplate messagingTemplate = new MessagingTemplate(this.controlBusChannel);
 		assertThat(messagingTemplate.convertSendAndReceive("@pausable.isRunning()", Boolean.class)).isEqualTo(false);
 		this.controlBusChannel.send(new GenericMessage<>("@pausable.start()"));
@@ -1162,6 +1171,11 @@ public class EnableIntegrationTests {
 			return new QueueChannel();
 		}
 
+		@Bean
+		public PollableChannel messageChannel2() {
+			return new QueueChannel();
+		}
+
 		@Bean
 		public QueueChannel numberChannel() {
 			QueueChannel channel = new QueueChannel();
@@ -1354,6 +1368,7 @@ public class EnableIntegrationTests {
 
 		@InboundChannelAdapter(value = "messageChannel", poller = @Poller(fixedDelay = "${poller.interval}",
 				maxMessagesPerPoll = "1"))
+		@InboundChannelAdapter(value = "messageChannel2", poller = @Poller(fixedDelay = "100"))
 		public Message<?> message() {
 			return MessageBuilder.withPayload("bar").setHeader("foo", "FOO").build();
 		}

src/reference/asciidoc/configuration.adoc

@@ -301,7 +301,7 @@ public class ThingService {
 ----
 ====
 
-You can also use the  `@Headers` annotation to provide all of the message headers as a `Map`, as the following example shows:
+You can also use the  `@Headers` annotation to provide all the message headers as a `Map`, as the following example shows:
 
 ====
 [source,java]
@@ -354,7 +354,7 @@ The `MessageHandler` instances (`MessageSource` instances) are also eligible to
 
 Starting with version 4.0, all messaging annotations provide `SmartLifecycle` options (`autoStartup` and `phase`) to allow endpoint lifecycle control on application context initialization.
 They default to `true` and `0`, respectively.
-To change the state of an endpoint (such as ` start()` or `stop()`), you can obtain a reference to the endpoint bean by using the `BeanFactory` (or autowiring) and invoke the methods.
+To change the state of an endpoint (such as `start()` or `stop()`), you can obtain a reference to the endpoint bean by using the `BeanFactory` (or autowiring) and invoke the methods.
 Alternatively, you can send a command message to the `Control Bus` (see <<./control-bus.adoc#control-bus,Control Bus>>).
 For these purposes, you should use the `beanName` mentioned earlier in the preceding paragraph.
 
@@ -380,6 +380,18 @@ Thing1 dependsOnSPCA(@Qualifier("someInboundAdapter") @Lazy SourcePollingChannel
 ====
 =====
 
+Starting with version 6.0, all the messaging annotations are `@Repeatable` now, so several of the same type can be declared on the same service method with the meaning to create as many endpoints as those annotations are repeated:
+====
+[source, java]
+----
+@Transformer(inputChannel = "inputChannel1", outputChannel = "outputChannel1")
+@Transformer(inputChannel = "inputChannel2", outputChannel = "outputChannel2")
+public String transform(String input) {
+    return input.toUpperCase();
+}
+----
+====
+
 [[configuration-using-poller-annotation]]
 ==== Using the `@Poller` Annotation
 

src/reference/asciidoc/whats-new.adoc

@@ -26,8 +26,10 @@ 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.
+The messaging annotations are now `@Repeatable` and the same type can be declared several times on the same service method.
+The messaging annotations don't require a `poller` attribute as an array of `@Poller` anymore.
+
+See <<./configuration.adoc#annotations,Annotation Support>> for more information.
 
 [[x6.0-http]]
 === HTTP Changes