Minor missing generic return

src/main/java/io/vertx/core/Future.java

@@ -106,7 +106,7 @@ static <T> Future<T> failedFuture(String failureMessage) {
    *
    */
   @Fluent
-  Future setHandler(Handler<AsyncResult<T>> handler);
+  Future<T> setHandler(Handler<AsyncResult<T>> handler);
 
   /**
    * Set the result. Any handler will be called, if there is one, and the future will be marked as completed.