TapDownDetails constructor Null safety
- {Offset globalPosition = Offset.zero,
 - Offset? localPosition,
 - PointerDeviceKind? kind}
 
Creates details for a GestureTapDownCallback.
The globalPosition argument must not be null.
Implementation
TapDownDetails({
  this.globalPosition = Offset.zero,
  Offset? localPosition,
  this.kind,
}) : assert(globalPosition != null),
     localPosition = localPosition ?? globalPosition;