* Improve AmqpClientMessageProducer.processRequest Javadoc

mentioning that `requestMessage` param is out of use
* Be more specific with the type for `UnsupportedOperationException`
in the `IntegrationRabbitAmqpMessageListener`

Author: artembilan

spring-integration-amqp/src/main/java/org/springframework/integration/amqp/inbound/AmqpClientMessageProducer.java

@@ -182,7 +182,7 @@ public boolean isPaused() {
 	/**
 	 * Use as {@link java.util.function.BiConsumer} for the {@link IntegrationRabbitAmqpMessageListener}.
 	 * @param messageToSend the message to produce from this endpoint.
-	 * @param requestMessage the request AMQP message.
+	 * @param requestMessage the request AMQP message. Ignored in this implementation.
 	 */
 	private void processRequest(Message<?> messageToSend,
 			org.springframework.amqp.core.@Nullable Message requestMessage) {

spring-integration-amqp/src/main/java/org/springframework/integration/amqp/inbound/IntegrationRabbitAmqpMessageListener.java

@@ -129,7 +129,8 @@ private Message<?> toSpringMessage(org.springframework.amqp.core.Message message
 
 	@Override
 	public void onMessage(org.springframework.amqp.core.Message message) {
-		throw new UnsupportedOperationException("The 'RabbitAmqpMessageListener' does not implement 'onMessage()'");
+		throw new UnsupportedOperationException(
+				"The 'IntegrationRabbitAmqpMessageListener' does not implement 'onMessage()'");
 	}
 
 	/**