public boolean onTouchEvent(MotionEvent event) {
    if (!isControllerValid()) {
      return false;
    }
    // NULLSAFE_FIXME[Nullable Dereference]
    return mController.onTouchEvent(event);
  }
Forwards the touch event to the controller.

@param event touch event to handle
@return whether the event was handled or not
drawee/src/main/java/com/facebook/drawee/view/DraweeHolder.java