import 'package:flutter_background_service/flutter_background_service.dart';class 
     ReminderService extends BackgroundService {
      @override
      Future<void> onInit() async {
        // Register a callback to be called when the service is started
        BackgroundService.onServiceStarted.listen((_) {
          // Start checking for due reminders
          _checkDueReminders();
        });
    
        // Register a callback to be called when the service is stopped
        BackgroundService.onServiceStopped.listen((_) {
          // Stop checking for due reminders
        });
      }
    
      Future<void> _checkDueReminders() async {
        // Get the list of all due reminders
        final List<Reminder> dueReminders = await ReminderRepository.getDueReminders();
    
        // For each due reminder, send a notification to the user
        for (final Reminder reminder in dueReminders) {
          await BackgroundService.sendNotification(
            title: 'Reminder',
            body: reminder.message,
          );
        }
      }
    }

我试图为我的项目做一个服务，我做了一个文件ReminderService，然后我添加了flutter_background_service：^2.0.0并做了pubget和一切，但我仍然面临错误Undefined name 'BackgroundService'。我试过扑干净，一切仍然有同样的问题