如何向TabBar添加凹槽以将FloatingActionButton放入其中

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('TabBar with FloatingActionButton'),
        ),
        body: Center(
          child: Text('Content goes here'),
        ),
        bottomNavigationBar: BottomAppBar(
          shape: CircularNotchedRectangle(),
          child: Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: <Widget>[
              IconButton(
                icon: Icon(Icons.menu),
                onPressed: () {},
              ),
              IconButton(
                icon: Icon(Icons.search),
                onPressed: () {},
              ),
            ],
          ),
        ),
        floatingActionButton: FloatingActionButton(
          child: Icon(Icons.add),
          onPressed: () {},
        ),
        floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
      ),
    );
  }
}