Dart APIunself_componentFloatScaffoldleading leading property Null safety Widget? leading final Implementation final Widget? leading; unself_component unself_component FloatScaffold leading property FloatScaffold class Constructors FloatScaffold Properties hashCode key leading middle runtimeType trailing Methods build createElement debugDescribeChildren debugFillProperties noSuchMethod toDiagnosticsNode toString toStringDeep toStringShallow toStringShort Operators operator ==