Dart APIunself_componentUnselfSliverNavigationBarlargeTitle largeTitle property Null safety Widget? largeTitle final Implementation final Widget? largeTitle; unself_component unself_component UnselfSliverNavigationBar largeTitle property UnselfSliverNavigationBar class Constructors UnselfSliverNavigationBar 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 ==