GH-2708: Make messaging annotations as repeatable

Fixes #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

Author: artembilan

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

@@ -18,6 +18,7 @@
 
 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 @@
 @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 @@
 
 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 @@
 @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 @@
 
 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 @@
 @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 @@
 
 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 @@
 @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 @@
 
 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 @@
 @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 @@
 
 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 @@
 @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 @@
 
 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 @@
 @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();
+
+}