Error when use anything(); in Android testing incompatible types required: Matcher

I run the code belows and got error at return anything();

error: incompatible types
required: Matcher <View>
found:    Matcher <Object>

/** 
     * Perform action of waiting until UI thread is free. <p/> E.g.: onView(isRoot()).perform(waitUntilIdle());
     * @return
     */
    public static ViewAction waitUntilIdle(){
      return new ViewAction(){
        @Override public Matcher<View> getConstraints(){
          return anything();
        }
        @Override public String getDescription(){
          return "wait until UI thread is free";
        }
        @Override public void perform(    final UiController uiController,    final View view){
          uiController.loopMainThreadUntilIdle();
        }
      }
    ;
    }

Any ideas?