Remove @UnsubscribeEvent

The STOMP UNSUBSCRIBE message does not have a destination header so
there is no obvious simple way to do a mapping and the need for it
is not clear yet.

Author: rstoyanchev

spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/UnsubscribeEvent.java

@@ -65,7 +65,6 @@
 import org.springframework.messaging.simp.SimpMessageType;
 import org.springframework.messaging.simp.SimpMessagingTemplate;
 import org.springframework.messaging.simp.annotation.SubscribeEvent;
-import org.springframework.messaging.simp.annotation.UnsubscribeEvent;
 import org.springframework.messaging.simp.annotation.support.PrincipalMethodArgumentResolver;
 import org.springframework.messaging.simp.annotation.support.SendToMethodReturnValueHandler;
 import org.springframework.messaging.simp.annotation.support.SubscriptionMethodReturnValueHandler;
@@ -120,8 +119,6 @@ public class AnnotationMethodMessageHandler implements MessageHandler, Applicati
 
 	private Map<MappingInfo, HandlerMethod> subscribeMethods = new HashMap<MappingInfo, HandlerMethod>();
 
-	private Map<MappingInfo, HandlerMethod> unsubscribeMethods = new HashMap<MappingInfo, HandlerMethod>();
-
 	private final Map<Class<?>, ExceptionHandlerMethodResolver> exceptionHandlerCache =
 			new ConcurrentHashMap<Class<?>, ExceptionHandlerMethodResolver>(64);
 
@@ -308,7 +305,6 @@ protected final void detectHandlerMethods(Object handler) {
 
 		initHandlerMethods(handler, handlerType, MessageMapping.class, this.messageMethods);
 		initHandlerMethods(handler, handlerType, SubscribeEvent.class, this.subscribeMethods);
-		initHandlerMethods(handler, handlerType, UnsubscribeEvent.class, this.unsubscribeMethods);
 	}
 
 	private <A extends Annotation> void initHandlerMethods(Object handler, Class<?> handlerType,
@@ -365,9 +361,6 @@ public void handleMessage(Message<?> message) throws MessagingException {
 		else if (SimpMessageType.SUBSCRIBE.equals(messageType)) {
 			handleMessageInternal(message, this.subscribeMethods);
 		}
-		else if (SimpMessageType.UNSUBSCRIBE.equals(messageType)) {
-			handleMessageInternal(message, this.unsubscribeMethods);
-		}
 	}
 
 	private void handleMessageInternal(Message<?> message, Map<MappingInfo, HandlerMethod> handlerMethods) {