Dart APIsettings_listSettingsListPageonSelectData onSelectData property Null safety VoidCallback onSelectData final Implementation final VoidCallback onSelectData; unself_settings_list settings_list SettingsListPage onSelectData property SettingsListPage class Constructors SettingsListPage Properties hashCode key onSelectAppearance onSelectData onSelectFeedback onSelectLicense onSelectPrivacy onSelectTerms runtimeType trailing Methods build createElement debugDescribeChildren debugFillProperties noSuchMethod toDiagnosticsNode toString toStringDeep toStringShallow toStringShort Operators operator ==