initialize() fails when called from a headless task

[jweidner-mbible]

I use the following class to display a notification.

import 'package:flutter_local_notifications/flutter_local_notifications.dart';

class NotificationsService {

  static void showNotification( String message, { String title = ''} ) async {
    var platformChannelSpecifics = NotificationDetails(AndroidNotificationDetails( "id2", "name2", "description2" ), IOSNotificationDetails());

    // Initialize local notifications plugin
    FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();
    var initializationSettings =
    InitializationSettings(
        AndroidInitializationSettings("ic_launcher"),
        IOSInitializationSettings());
    await flutterLocalNotificationsPlugin.initialize(initializationSettings);
    await flutterLocalNotificationsPlugin.show(0, title, message, platformChannelSpecifics);
  }
}

This seems to work fine when called in response to some UI event while my app is running. However, I am integrating with flutter_background_geolocation plugin and would like to display a notification when a geofence event occurs. I'm using
bg.BackgroundGeolocation.registerHeadlessTask(headlessTask). However, if my headlessTask method calls the above showNotification method, it fails and logs the error:

[ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: MissingPluginException(No implementation found for method initialize on channel dexterous.com/flutter/local_notifications)
#0 MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:154:7)
#1 MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:329:12)
#2 AndroidFlutterLocalNotificationsPlugin.initialize (package:flutter_local_notifications/src/platform_flutter_local_notifications.dart:67:27)
#3 FlutterLocalNotificationsPlugin.initialize (package:flutter_local_notifications/src/flutter_local_notifications_plugin.dart:97:13)
#4 NotificationsService.showNotification (package:flutter_tic_tac_toe/services/notifications.dart:14:43)
#5 headlessTask (package:flutter_tic_tac_toe/main.dart:98:26)

[jweidner-mbible]

Dupe of #238