Dart APIunself_componentTextAreacontroller controller property Null safety TextEditingController? controller final Implementation final TextEditingController? controller; unself_component unself_component TextArea controller property TextArea class Constructors TextArea Properties autofocus controller hashCode key onChanged onTap runtimeType Methods build createElement debugDescribeChildren debugFillProperties noSuchMethod toDiagnosticsNode toString toStringDeep toStringShallow toStringShort Operators operator ==