anchor.diff:      _splashes ??= new HashSet<InteractiveInkFeature>();
       _splashes.add(splash);
       _currentSplash = splash;
  +    if (widget.onTapDown != null) {
  +      widget.onTapDown(details);
  +    }
       updateKeepAlive();
       updateHighlight(true);
     }
  
positive.code:   void _handleTapCancel() {
      _currentSplash?.cancel();
      _currentSplash = null;
      updateHighlight(false);
    }
  
  
negative.code: 
    /// Called when the user taps this part of the material.
    final GestureTapCallback onTap;
  
    /// Called when the user taps down this part of the material.
    final GestureTapDownCallback onTapDown;
  
    /// Called when the user cancels a tap that was started on this part of the
    /// material.
    final GestureTapCallback onTapCancel;
  
    /// Called when the user double taps this part of the material.
    final GestureTapCallback onDoubleTap;
  