final List<Contact> contacts = List();

Alguém pode me ajudar essa linha de código no meu contacs_list.dart está dando erro e não sei como resolver.

import 'package:flutter/material.dart';
import 'contact_form.dart';
import 'package:bytebank/models/contact.dart';

class ContactsList extends StatelessWidget {
  final List<Contact> contacts = List();

  @override
  Widget build(BuildContext context) {
    contacts.add(Contact('Gabriel', 1000));
    contacts.add(Contact('Amanda', 2000));
    return Scaffold(
      appBar:
          AppBar(title: Text('Contacts'), backgroundColor: Colors.green[900]),
      body: ListView.builder(
        itemBuilder: (context, index) {
          final Contact contact = contacts[index];
          return _ContactItem(contact);
        },
        itemCount: contacts.length,
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          Navigator.of(context)
              .push(
                MaterialPageRoute(
                  builder: (context) => ContactForm(),
                ),
              )
              .then((newContact) => debugPrint(newContact.toString()));
        },
        child: Icon(Icons.add),
      ),
    );
  }
}

class _ContactItem extends StatelessWidget {
  final Contact contact;
  _ContactItem(this.contact);

  @override
  Widget build(BuildContext context) {
    return Card(
      child: ListTile(
        title: Text(
          contact.name,
          style: TextStyle(fontSize: 24.0),
        ),
        subtitle: Text(
          contact.accountNumber.toString(),
          style: TextStyle(fontSize: 16.0),
        ),
      ),
    );
  }
}