Dart APIunself_componentPairingScrollControllergroup group property Null safety PairingScrollControllerGroup group final Implementation final PairingScrollControllerGroup group; unself_component unself_component PairingScrollController group property PairingScrollController class Constructors PairingScrollController Properties automaticallyInheritForPlatforms child controller group hashCode key runtimeType scrollDirection Methods createElement debugDescribeChildren debugFillProperties noSuchMethod toDiagnosticsNode toString toStringDeep toStringShallow toStringShort updateShouldNotify Operators operator == Static methods of