GH-1269: @RabbitListener: Allow other Annotations

Resolves #1269

Previously, a parameter annotated with a "foreign" annoation (e.g. `@Validated`)
would not be considered as an eligible payload conversion target; it must also
have been annotated with `@Payload`.

- remove the check for zero annotations
- add a check that the method is not annotated with both `@Payload` and `@Header`
  - ignore if it does, with a warn log, to be consistent with previous behavior.
  - in a future release we might consider this to be fatal.

**cherry-pick to 2.2.x**

Author: garyrussell

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/listener/adapter/MessagingMessageListenerAdapter.java

@@ -34,6 +34,7 @@
 import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
+import org.springframework.messaging.handler.annotation.Header;
 import org.springframework.messaging.handler.annotation.Payload;
 import org.springframework.messaging.support.MessageBuilder;
 import org.springframework.remoting.support.RemoteInvocationResult;
@@ -333,12 +334,21 @@ private Type determineInferredType() {
 			for (int i = 0; i < this.method.getParameterCount(); i++) {
 				MethodParameter methodParameter = new MethodParameter(this.method, i);
 				/*
-				 * We're looking for a single non-annotated parameter, or one annotated with @Payload.
+				 * We're looking for a single parameter, or one annotated with @Payload.
 				 * We ignore parameters with type Message because they are not involved with conversion.
 				 */
+				boolean isHeader = methodParameter.hasParameterAnnotation(Header.class);
+				boolean isPayload = methodParameter.hasParameterAnnotation(Payload.class);
+				if (isHeader && isPayload) {
+					if (MessagingMessageListenerAdapter.this.logger.isWarnEnabled()) {
+						MessagingMessageListenerAdapter.this.logger.warn(this.method.getName()
+							+ ": Cannot annotate a parameter with both @Header and @Payload; "
+							+ "ignored for payload conversion");
+					}
+				}
 				if (isEligibleParameter(methodParameter)
-						&& (methodParameter.getParameterAnnotations().length == 0
-						|| methodParameter.hasParameterAnnotation(Payload.class))) {
+						&& (!isHeader || isPayload) && !(isHeader && isPayload)) {
+
 					if (genericParameterType == null) {
 						genericParameterType = extractGenericParameterTypFromMethodParameter(methodParameter);
 					}

spring-rabbit/src/test/java/org/springframework/amqp/rabbit/annotation/EnableRabbitIntegrationTests.java

@@ -130,6 +130,7 @@
 import org.springframework.transaction.annotation.EnableTransactionManagement;
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.util.ErrorHandler;
+import org.springframework.validation.annotation.Validated;
 
 import com.rabbitmq.client.Channel;
 import com.rabbitmq.http.client.Client;
@@ -1137,8 +1138,9 @@ public void handleIt(Date body) {
 
 		}
 
-		@RabbitListener(id = "different", queues = "differentTypes", containerFactory = "jsonListenerContainerFactory")
-		public void handleDifferent(Foo2 foo) {
+		@RabbitListener(id = "different", queues = "differentTypes",
+				containerFactory = "jsonListenerContainerFactoryNoClassMapper")
+		public void handleDifferent(@Validated Foo2 foo) {
 			foos.add(foo);
 			latch.countDown();
 		}
@@ -1581,6 +1583,19 @@ public SimpleRabbitListenerContainerFactory jsonListenerContainerFactory() {
 			return factory;
 		}
 
+		@Bean
+		public SimpleRabbitListenerContainerFactory jsonListenerContainerFactoryNoClassMapper() {
+			SimpleRabbitListenerContainerFactory factory = new SimpleRabbitListenerContainerFactory();
+			factory.setConnectionFactory(rabbitConnectionFactory());
+			factory.setErrorHandler(errorHandler());
+			factory.setConsumerTagStrategy(consumerTagStrategy());
+			Jackson2JsonMessageConverter messageConverter = new Jackson2JsonMessageConverter();
+			factory.setMessageConverter(messageConverter);
+			factory.setReceiveTimeout(10L);
+			factory.setConcurrentConsumers(2);
+			return factory;
+		}
+
 		@Bean
 		public MeterRegistry meterRegistry() {
 			return new SimpleMeterRegistry();
@@ -2178,7 +2193,7 @@ public String foo2(Foo2 foo2, @Header("amqp_consumerQueue") String queue) {
 		}
 
 		@RabbitListener(queues = "test.converted.args2")
-		public String foo2a(@Payload Foo2 foo2, @Header("amqp_consumerQueue") String queue) {
+		public String foo2a(Foo2 foo2, @Header("amqp_consumerQueue") String queue) {
 			return foo2 + queue;
 		}