Dart APIunself_componentUnselfExtendedSliverNavigationBartrailing trailing property Null safety Widget? trailing final Implementation final Widget? trailing; unself_component unself_component UnselfExtendedSliverNavigationBar trailing property UnselfExtendedSliverNavigationBar class Constructors UnselfExtendedSliverNavigationBar Properties automaticallyImplyLeading automaticallyImplyTitle backgroundColor border brightness hashCode heroTag key largeTitle leading middle opaque padding previousPageTitle runtimeType stretch trailing transitionBetweenRoutes Methods createElement createState debugDescribeChildren debugFillProperties noSuchMethod toDiagnosticsNode toString toStringDeep toStringShallow toStringShort Operators operator ==