build method
Override this method to build widgets that depend on the state of the listenable (e.g., the current value of the animation).
Implementation
@override
Widget build(BuildContext context) => FModalBarrier(
  filter: filter == null ? null : filter!(animation.value),
  onDismiss: onDismiss,
  semanticsLabel: semanticsLabel,
  barrierSemanticsDismissible: barrierSemanticsDismissible,
  clipDetailsNotifier: clipDetailsNotifier,
  semanticsOnTapHint: semanticsOnTapHint,
);