Flutter const:需要在sub上使用它吗？

class MyWidget extends StatelessWidget {
  final String title;

  const MyWidget({Key? key, required this.title}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const Text('Hello, World!'); // 这里Text是一个const Widget
  }
}

void main() {
  runApp(const MaterialApp(
    home: Scaffold(
      appBar: AppBar(title: Text('My App')),
      body: MyWidget(title: 'Flutter'),
    ),
  ));
}

class MyChildWidget extends StatelessWidget {
  final String message;

  const MyChildWidget({Key? key, required this.message}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Text(message);
  }
}

class MyParentWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        const MyChildWidget(message: 'This is a constant child widget'),
        MyChildWidget(message: 'This is a non-constant child widget'),
      ],
    );
  }
}