如何在Flutter中一次只扩展一个ExpansionTile

import 'package:flutter/material.dart';

class MyExpansionPanelList extends StatefulWidget {
  @override
  _MyExpansionPanelListState createState() => _MyExpansionPanelListState();
}

class _MyExpansionPanelListState extends State<MyExpansionPanelList> {
  List<Item> _items = generateItems(); // 用于存储ExpansionPanel的状态的列表

  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
      child: Container(
        child: _buildPanel(),
      ),
    );
  }

  Widget _buildPanel() {
    return ExpansionPanelList(
      elevation: 1,
      expandedHeaderPadding: EdgeInsets.all(0),
      expansionCallback: (int index, bool isExpanded) {
        setState(() {
          _items[index].isExpanded = !isExpanded;
        });
      },
      children: _items.map<ExpansionPanel>((Item item) {
        return ExpansionPanel(
          headerBuilder: (BuildContext context, bool isExpanded) {
            return ListTile(
              title: Text(item.headerValue),
            );
          },
          body: ListTile(
            title: Text(item.expandedValue),
          ),
          isExpanded: item.isExpanded,
        );
      }).toList(),
    );
  }
}

class Item {
  Item({
    required this.expandedValue,
    required this.headerValue,
    this.isExpanded = false,
  });

  String expandedValue;
  String headerValue;
  bool isExpanded;
}

List<Item> generateItems() {
  return List<Item>.generate(1, (int index) {
    return Item(
      headerValue: 'ExpansionTile',
      expandedValue: 'ExpansionTile的内容',
    );
  });
}

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'ExpansionTile Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: Text('ExpansionTile Demo'),
        ),
        body: MyExpansionPanelList(),
      ),
    );
  }
}