Flutter using FutureProvider to get data from ChangeNotifier method

Question

After implementing a simple ChangeNotifier i want to get data from one of this class method which that return a Future, but i can't define FutureProvider for this class, please see my code

main.dart:

@override
Widget build(BuildContext context) {
  return MultiProvider(
    providers: [
      ChangeNotifierProvider(
        create: (_) => Vpns(),
      )
    ],
    child: MaterialApp(
      //...
      home: SplashScreen(),
    ),
  );
}

Vpns class:

import 'dart:async';
import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:flutter_openvpn/flutter_openvpn.dart';
import 'package:http/http.dart' as http;

class Vpn with ChangeNotifier {
  final String id;
  final String name;

  Vpn({
    required this.id,
    required this.name,
  });

  get speed => null;
}

class Vpns with ChangeNotifier {
  
  late List<Vpn> _vpns;
  List<Vpn> get vpns => [..._vpns];
  //
  set connectionState(String connectionState) {
    _connectionState = connectionState;
    notifyListeners();
  }

  late Vpn? _connectedVpn;
  Vpn get connectedVpn => _connectedVpn!;

 ///

  Future<void> fetchVpns() async {
    List<Vpn> _newVpns = [];
    ///
    notifyListeners();
  }

  ///
}

as you can see i have a fetchVpns in Vpns class which i should use FutureProvider to get data from that. now how can i define in this sample code:

this below code is wrong and i should fix that

return Scaffold(
    body: FutureProvider<Vpn>(
      initialData: null,
      builder: (_)=>Provider.of<Vpns>(context, listen: false).fetchVpns(),
      child: ListView(
        children: <Widget>[
          ///...
        ],
      ),
    ));