Dart APIunself_componentUnAppPagedescription description property Null safety Widget? description final Implementation final Widget? description; unself_component unself_component UnAppPage description property UnAppPage class Constructors UnAppPage Properties description hashCode implyLeading isImmersive key leading name runtimeType slivers trailing Methods build createElement debugDescribeChildren debugFillProperties noSuchMethod toDiagnosticsNode toString toStringDeep toStringShallow toStringShort Operators operator ==