Add basic javadoc to spring-messaging annotations

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/MessageBody.java

@@ -22,9 +22,12 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.springframework.messaging.Message;
+
 
 /**
- * Annotation indicating a method parameter should be bound to the body of a message.
+ * Annotation indicating a method parameter should be bound to the body of a
+ * {@link Message}.
  *
  * @author Rossen Stoyanchev
  * @since 4.0

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/MessageExceptionHandler.java

@@ -25,6 +25,10 @@ import java.lang.annotation.Target;
 
 
 /**
+ * Annotation for handling exceptions from message-handling methods within specific
+ * handler methods.
+ *
+ *
  * @author Rossen Stoyanchev
  * @since 4.0
  */

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/MessageMapping.java

@@ -22,7 +22,13 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.springframework.messaging.Message;
+
+
 /**
+ * Annotation for mapping a {@link Message} onto specific handler handler methods based on
+ * the destination for the message.
+ *
  * @author Rossen Stoyanchev
  * @since 4.0
  */

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/ReplyTo.java

@@ -22,8 +22,13 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.springframework.messaging.Message;
+
 
 /**
+ * Annotation that indicates a method's return value should be converted to
+ * a {@link Message} and sent to the specified destination.
+ *
  * @author Rossen Stoyanchev
  * @since 4.0
  */

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

@@ -22,10 +22,23 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.springframework.messaging.Message;
+import org.springframework.messaging.simp.SimpMessageHeaderAccessor;
+
 
 /**
+ * Annotation that can be used on methods processing an input message to indicate that the
+ * method's return value should be converted to a {@link Message} and sent to the
+ * specified destination with the prefix <code>"/user/{username}"</code> automatically
+ * prepended with the user information expected to be the input message header
+ * {@link SimpMessageHeaderAccessor#USER_HEADER}. Such user destinations may need to be
+ * further resolved to actual destinations.
+ *
  * @author Rossen Stoyanchev
  * @since 4.0
+ *
+ * @see org.springframework.messaging.handler.annotation.ReplyTo
+ * @see org.springframework.messaging.simp.handler.UserDestinationMessageHandler
  */
 @Target(ElementType.METHOD)
 @Retention(RetentionPolicy.RUNTIME)

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

@@ -24,6 +24,9 @@ import java.lang.annotation.Target;
 
 
 /**
+ * Annotation for mapping subscription events onto specific handler handler methods based
+ * on the destination for the message (e.g. STOMP SUBSCRIBE message).
+ *
  * @author Rossen Stoyanchev
  * @since 4.0
  */

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

@@ -24,6 +24,9 @@ import java.lang.annotation.Target;
 
 
 /**
+ * Annotation for mapping unsubscribe events onto specific handler handler methods based
+ * on the destination for the message (e.g. STOMP UNSUBSCRIBE message).
+ *
  * @author Rossen Stoyanchev
  * @since 4.0
  */