Dart APIunself_componentUnSliverArtBarname name property Null safety Widget name final Implementation final Widget name; unself_component unself_component UnSliverArtBar name property UnSliverArtBar class Constructors UnSliverArtBar Properties action background description emoji hashCode isImmersive key leading name runtimeType trailing Methods createElement createState debugDescribeChildren debugFillProperties noSuchMethod toDiagnosticsNode toString toStringDeep toStringShallow toStringShort Operators operator ==