why can't I see the class Audio Source on flutter?

my pubspec

dependencies:

flutter:

sdk: flutter  

audioplayers: ^5.2.1

cupertino_icons: ^1.0.6

sourc code

``` import 'package:flutter/material.dart';

import 'package:audioplayers/audioplayers.dart';

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

class AudioPlayerApp extends StatelessWidget {@overrideWidget build(BuildContext context) {return MaterialApp(home: AudioPlayerWidget(),);}}

class AudioPlayerWidget extends StatefulWidget {@override_AudioPlayerWidgetState createState() => _AudioPlayerWidgetState();}

class _AudioPlayerWidgetState extends State<AudioPlayerWidget> {late AudioPlayer _audioPlayer;late AudioSource _audioSource;

@overridevoid initState() {super.initState();_audioPlayer = AudioPlayer();_audioSource = UrlSource('http://myradio.com/test');}

@overrideWidget build(BuildContext context) {return Scaffold(appBar: AppBar(title: Text('Audio Player'),),body: Center(child: IconButton(icon: Icon(Icons.play_circle_filled),onPressed: () async {await _audioPlayer.play(_audioSource);},),),);}

@overridevoid dispose() {_audioPlayer.dispose();super.dispose();}} ```

I keep getting these logs lib/main.dart:24:8: Error: Type 'AudioSource' not found. late AudioSource _audioSource; ^^^^^^^^^^^ lib/main.dart:24:8: Error: 'AudioSource' isn't a type. late AudioSource _audioSource; ^^^^^^^^^^^ Target kernel_snapshot failed: Exception

Change late AudioSource _audioSource; to late Source _audioSource; Because Source is the parent class of UrlSource.

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

class AudioPlayerApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(home: AudioPlayerWidget());
  }
}

class AudioPlayerWidget extends StatefulWidget {
  @override
  _AudioPlayerWidgetState createState() => _AudioPlayerWidgetState();
}

class _AudioPlayerWidgetState extends State<AudioPlayerWidget> {
  late AudioPlayer _audioPlayer;
  late Source _audioSource;

  @override
  void initState() {
    super.initState();
    _audioPlayer = AudioPlayer();
    _audioSource = UrlSource('http://myradio.com/test');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Audio Player'),
      ),
      body: Center(
        child: IconButton(
          icon: Icon(Icons.play_circle_filled),
          onPressed: () async {
            await _audioPlayer.play(_audioSource);
          },
        ),
      ),
    );
  }

  @override
  void dispose() {
    _audioPlayer.dispose();
    super.dispose();
  }
}