Dart APIunself_componentUnSheetsecondAnimation secondAnimation property Null safety AnimationController? secondAnimation final Implementation final AnimationController? secondAnimation; unself_component unself_component UnSheet<T> secondAnimation property UnSheet class Constructors UnSheet Properties animationCurve arguments backgroundColor barrierColor bounce child clipBehavior closeProgressThreshold duration elevation enableDrag expand hashCode isDismissible key name overlayStyle previousRouteAnimationCurve restorationId runtimeType secondAnimation settings shadow shape topRadius transitionBackgroundColor useRootNavigator Methods canUpdate createRoute noSuchMethod toString Operators operator ==