如何在颤动中使用CircularNotchedRectangle向BottomAppBar添加圆角

import 'package:flutter/material.dart';

class MyBottomAppBar extends StatefulWidget {
  @override
  _MyBottomAppBarState createState() => _MyBottomAppBarState();
}

class _MyBottomAppBarState extends State<MyBottomAppBar> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('CircularNotchedRectangle'),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {},
        child: Icon(Icons.add),
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
      bottomNavigationBar: BottomAppBar(
        shape: CircularNotchedRectangle(),
        child: Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: <Widget>[
            IconButton(
              icon: Icon(Icons.menu),
              onPressed: () {},
            ),
            IconButton(
              icon: Icon(Icons.search),
              onPressed: () {},
            ),
          ],
        ),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: MyBottomAppBar(),
  ));
}