Expand item inside list of items - ExpansionPanel in flutter

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
  static const String _title = 'Flutter Code Sample';
  @
override

  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Scaffold(
        appBar: AppBar(title: const Text(_title)),
        body: const MyStatefulWidget(),
      ),
    );
  }
}

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

List<Item> generateItems(int numberOfItems) {
  return List<Item>.generate(numberOfItems, (int index) {
    return Item(
      headerValue: 'Item 
$
index
',
      expandedValue: 'This is item number 
$
index
',
    );
  });
}

class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({Key? key}) : super(key: key);
  @
override

  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  final List<Item> _data = generateItems(8);
  @
override

  Widget build(BuildContext context) {
    return SingleChildScrollView(
      child: Container(
        child: _buildPanel(),
      ),
    );
  }
  Widget _buildPanel() {
    return ExpansionPanelList(
      expansionCallback: (panelIndex, isExpanded) {
        setState(() {
          _data[panelIndex].isExpanded = !isExpanded;
        });
      },
      children: _data

          .map((e) => ExpansionPanel(
              isExpanded: e.isExpanded,
              headerBuilder: (context, isExpanded) =>
                  ListTile(title: Text(e.headerValue)),
              body: ListTile(
                title: Text(e.expandedValue),
              )))
          .toList(),
    );
  }
}