🐛 [firebase_messaging] RemoteMessage object never contains data payload

Bug report

Describe the bug

I am sending a data payload with my message server side and there is an empty Map<String, dynamic> object client-side.

Steps to reproduce

Steps to reproduce the behavior:

Run the sample code
Use the token to send a push notification to the device
Send the notification with a data payload (i am joining the code server side in Python if this helps)
See in the logs that data is always empty, from background handler and from onMessage

Expected behavior

The message.data should not be empty when providing data payload server side or from the Console.

Sample project

import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter/material.dart';

Future<void> firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  print("Data from background handler : ${message.data}");
  print("Notification from background handler : ${message.notification!.title}");
}

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(const TestApp());
}

class TestApp extends StatefulWidget {
  const TestApp({Key? key}) : super(key: key);

  @override
  State<TestApp> createState() => _TestAppState();
}

class _TestAppState extends State<TestApp> {

  void initMessaging() async {
    FirebaseMessaging.instance.getToken().then((token) {
      print("Token retrieved : $token");
      // TODO : use this token to send a notification from server
    });

    FirebaseMessaging.onMessage.listen((RemoteMessage message) {
      print("Date from message : ${message.data}");
      print("Notification from message : ${message.notification!.title}");
    });

    FirebaseMessaging.onBackgroundMessage(firebaseMessagingBackgroundHandler);
  }

  @override
  void initState() {
    initMessaging();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return const MaterialApp();
  }

}

Additional context

Server side code :

from firebase_admin import messaging

data = dict()
data["fake"] = "Fake content"
data["isWorking"] = False
title = "Title from Python"
image = None
photo = ""
content = "Notification content from Python"
tokens = ["token_you_retrieved_from_flutter"]

android_config = messaging.AndroidConfig(
        notification=messaging.AndroidNotification(
            image=image,
            body=content,
            title=title,
            priority="high",
            icon=photo
        ),
        data=data
    )
    apns_alert = messaging.ApsAlert(
        title=title,
        body=content,
        launch_image=photo
    )
    apns_config = messaging.APNSConfig(
        payload=messaging.APNSPayload(
            aps=messaging.Aps(
                alert=apns_alert,
                content_available=True,
            )
        ),
        fcm_options=messaging.APNSFCMOptions(
            image=image
        )
    )
    notification = messaging.MulticastMessage(
        data=data,
        tokens=tokens,
        apns=apns_config,
        android=android_config
    )
    response = messaging.send_multicast(notification)
    print(f'{response.success_count} notifications sent successfully.')

Flutter doctor

Run flutter doctor and paste the output below:

Click To Expand

``` [✓] Flutter (Channel stable, 2.5.3, on macOS 12.0.1 21A559 darwin-x64, locale fr-FR) [✓] Android toolchain - develop for Android devices (Android SDK version 31.0.0) [✓] Xcode - develop for iOS and macOS [✓] Chrome - develop for the web [✓] Android Studio (version 2020.3) [✓] VS Code (version 1.62.0) [✓] Connected device (3 available) • No issues found! ```

Flutter dependencies

Run flutter pub deps -- --style=compact and paste the output below:

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``` Dart SDK 2.14.4 Flutter SDK 2.5.3 myapptest 1.0.0+1 dependencies: - app_tracking_transparency 2.0.2+1 [flutter] - apple_maps_flutter 1.0.1 [flutter] - badges 2.0.1 [flutter] - cached_network_image 3.1.0+1 [flutter flutter_cache_manager octo_image cached_network_image_platform_interface cached_network_image_web] - camera 0.9.4+3 [camera_platform_interface camera_web flutter pedantic quiver flutter_plugin_android_lifecycle] - clipboard 0.1.3 [flutter] - cloud_functions 3.1.0 [cloud_functions_platform_interface cloud_functions_web firebase_core firebase_core_platform_interface flutter] - connectivity_plus 2.0.2 [flutter meta connectivity_plus_platform_interface connectivity_plus_linux connectivity_plus_macos connectivity_plus_web connectivity_plus_windows] - country_code_picker 2.0.2 [flutter modal_bottom_sheet collection universal_platform] - cross_connectivity 3.0.3 [flutter meta http rxdart connectivity connectivity_macos] - crypto 3.0.1 [collection typed_data] - cupertino_back_gesture 0.1.0 [flutter] - cupertino_icons 1.0.4 - disk_space 0.2.1 [flutter] - emoji_picker_flutter 1.0.7 [flutter shared_preferences] - extended_image 5.1.3 [extended_image_library flutter meta] - extended_tabs 2.3.0 [flutter] - firebase_analytics 8.3.4 [firebase_analytics_platform_interface firebase_analytics_web firebase_core flutter meta] - firebase_auth 3.2.0 [firebase_auth_platform_interface firebase_auth_web firebase_core firebase_core_platform_interface flutter meta] - firebase_core 1.10.0 [firebase_core_platform_interface firebase_core_web flutter meta] - firebase_crashlytics 2.3.0 [firebase_core firebase_core_platform_interface firebase_crashlytics_platform_interface flutter stack_trace] - firebase_dynamic_links 3.0.1 [firebase_core flutter] - firebase_messaging 11.1.0 [firebase_core firebase_core_platform_interface firebase_messaging_platform_interface firebase_messaging_web flutter meta] - firebase_performance 0.7.1+4 [firebase_core firebase_core_platform_interface firebase_performance_platform_interface firebase_performance_web flutter] - firebase_storage 10.1.0 [firebase_core firebase_core_platform_interface firebase_storage_platform_interface firebase_storage_web flutter] - flutter 0.0.0 [characters collection meta typed_data vector_math sky_engine] - flutter_app_badger 1.3.0 [flutter] - flutter_arc_text 0.5.0 [characters flutter] - flutter_contacts 1.1.1+2 [flutter] - flutter_facebook_auth 3.5.6 [flutter flutter_facebook_auth_platform_interface flutter_facebook_auth_web] - flutter_ffmpeg 0.4.2 [flutter] - flutter_image_compress 1.1.0 [flutter] - flutter_launcher_icons 0.9.2 [args image path yaml] - flutter_localizations 0.0.0 [flutter intl characters clock collection meta path typed_data vector_math] - flutter_sound_lite 8.4.2 [path_provider recase uuid provider path synchronized logger flutter flutter_sound_platform_interface flutter_sound_web] - flutter_staggered_grid_view 0.4.1 [flutter] - flutter_svg 0.23.0+1 [flutter meta path_drawing vector_math xml] - geocoding 2.0.1 [flutter geocoding_platform_interface] - geolocator 7.7.1 [flutter geolocator_platform_interface geolocator_android geolocator_apple geolocator_web] - google_fonts 2.1.0 [flutter http path_provider crypto] - google_maps_flutter 2.1.0 [flutter flutter_plugin_android_lifecycle google_maps_flutter_platform_interface] - google_mobile_ads 0.13.6 [meta flutter] - google_sign_in 5.2.1 [flutter google_sign_in_platform_interface google_sign_in_web meta] - http 0.13.4 [async http_parser meta path] - image_editor 1.0.2 [flutter] - in_app_review 2.0.3 [flutter in_app_review_platform_interface] - intl 0.17.0 [clock path] - modal_bottom_sheet 2.0.0 [flutter] - native_admob_flutter 1.5.0 [flutter] - path 1.8.0 - path_provider 2.0.6 [flutter path_provider_linux path_provider_macos path_provider_platform_interface path_provider_windows] - permission_handler 8.2.6 [flutter meta permission_handler_platform_interface] - photo_manager 1.3.9+1 [flutter] - progressive_image 2.0.0 [flutter] - provider 6.0.1 [collection flutter nested] - pull_to_refresh 2.0.0 [flutter] - rive 0.7.33 [collection flutter graphs http meta] - scrollable_positioned_list 0.2.2 [flutter collection] - share_plus 3.0.4 [meta mime flutter share_plus_platform_interface share_plus_linux share_plus_macos share_plus_windows share_plus_web] - shared_preferences 2.0.8 [flutter meta shared_preferences_linux shared_preferences_macos shared_preferences_platform_interface shared_preferences_web shared_preferences_windows] - sign_in_with_apple 3.2.0 [flutter meta] - sliver_tools 0.2.5 [flutter] - sqflite 2.0.0+4 [flutter sqflite_common path] - translator 0.1.7 [http] - url_launcher 6.0.12 [flutter meta url_launcher_linux url_launcher_macos url_launcher_platform_interface url_launcher_web url_launcher_windows] - uuid 3.0.5 [crypto] - video_compress 3.1.0 [flutter] - video_player 2.2.6 [flutter meta video_player_platform_interface video_player_web html] - video_thumbnail 0.4.3 [flutter] - visibility_detector 0.2.2 [flutter] - volume_watcher 2.0.1 [flutter] - web_socket_channel 2.1.0 [async crypto stream_channel] - webview_flutter 2.3.0 [flutter webview_flutter_android webview_flutter_platform_interface webview_flutter_wkwebview] dev dependencies: - flutter_lints 1.0.4 [lints] - flutter_test 0.0.0 [flutter test_api path fake_async clock stack_trace vector_math async boolean_selector characters charcode collection matcher meta source_span stream_channel string_scanner term_glyph typed_data] transitive dependencies: - archive 3.1.6 [crypto path] - args 2.3.0 - async 2.8.1 [collection meta] - boolean_selector 2.1.0 [source_span string_scanner] - cached_network_image_platform_interface 1.0.0 [flutter flutter_cache_manager] - cached_network_image_web 1.0.1 [flutter flutter_cache_manager cached_network_image_platform_interface] - camera_platform_interface 2.1.1 [cross_file flutter meta plugin_platform_interface stream_transform] - camera_web 0.2.1+1 [camera_platform_interface flutter flutter_web_plugins stream_transform] - characters 1.1.0 - charcode 1.3.1 - clock 1.1.0 - cloud_functions_platform_interface 5.0.14 [firebase_core flutter meta plugin_platform_interface] - cloud_functions_web 4.1.0 [cloud_functions_platform_interface firebase_core firebase_core_web flutter flutter_web_plugins js] - collection 1.15.0 - connectivity 3.0.6 [flutter meta connectivity_platform_interface connectivity_macos connectivity_for_web] - connectivity_for_web 0.4.0+1 [connectivity_platform_interface flutter_web_plugins flutter] - connectivity_macos 0.2.1+2 [flutter connectivity_platform_interface] - connectivity_platform_interface 2.0.1 [flutter meta plugin_platform_interface] - connectivity_plus_linux 1.1.0 [flutter connectivity_plus_platform_interface dbus meta nm] - connectivity_plus_macos 1.2.1 [connectivity_plus_platform_interface flutter] - connectivity_plus_platform_interface 1.1.0 [flutter meta plugin_platform_interface] - connectivity_plus_web 1.1.0+1 [connectivity_plus_platform_interface flutter_web_plugins flutter] - connectivity_plus_windows 1.2.0 [connectivity_plus_platform_interface flutter] - cross_file 0.3.2 [flutter js meta] - csslib 0.17.1 [source_span] - dbus 0.5.6 [args ffi meta pedantic xml] - extended_image_library 3.1.0 [crypto flutter http_client_helper path path_provider] - fake_async 1.2.0 [clock collection] - ffi 1.1.2 - file 6.1.2 [meta path] - firebase 9.0.2 [http http_parser js] - firebase_analytics_platform_interface 2.0.1 [flutter meta] - firebase_analytics_web 0.3.0+1 [firebase firebase_analytics_platform_interface flutter flutter_web_plugins meta] - firebase_auth_platform_interface 6.1.4 [firebase_core flutter meta plugin_platform_interface] - firebase_auth_web 3.2.0 [firebase_auth_platform_interface firebase_core firebase_core_web flutter flutter_web_plugins http_parser intl js meta] - firebase_core_platform_interface 4.1.0 [collection flutter meta plugin_platform_interface] - firebase_core_web 1.2.0 [firebase_core_platform_interface flutter flutter_web_plugins js meta] - firebase_crashlytics_platform_interface 3.1.6 [collection firebase_core flutter meta plugin_platform_interface] - firebase_messaging_platform_interface 3.0.9 [firebase_core flutter meta plugin_platform_interface] - firebase_messaging_web 2.1.0 [firebase_core firebase_core_web firebase_messaging_platform_interface flutter flutter_web_plugins js meta] - firebase_performance_platform_interface 0.0.1+7 [firebase_core flutter plugin_platform_interface] - firebase_performance_web 0.0.2 [firebase firebase_performance_platform_interface flutter flutter_web_plugins] - firebase_storage_platform_interface 4.0.6 [collection firebase_core flutter meta plugin_platform_interface] - firebase_storage_web 3.1.0 [async firebase_core firebase_core_web firebase_storage_platform_interface flutter flutter_web_plugins http js meta] - flutter_blurhash 0.6.0 [flutter meta pedantic] - flutter_cache_manager 3.1.3 [clock collection file flutter http path path_provider pedantic rxdart sqflite uuid] - flutter_facebook_auth_platform_interface 2.7.0 [flutter plugin_platform_interface] - flutter_facebook_auth_web 2.6.0+2 [flutter flutter_web_plugins js flutter_facebook_auth_platform_interface] - flutter_plugin_android_lifecycle 2.0.4 [flutter] - flutter_sound_platform_interface 8.4.2 [flutter meta plugin_platform_interface logger] - flutter_sound_web 8.4.2 [flutter_sound_platform_interface flutter logger flutter_web_plugins meta js] - flutter_web_plugins 0.0.0 [flutter js characters collection meta typed_data vector_math] - geocoding_platform_interface 2.0.1 [flutter meta plugin_platform_interface] - geolocator_android 2.1.0 [flutter geolocator_platform_interface] - geolocator_apple 1.2.2 [flutter geolocator_platform_interface] - geolocator_platform_interface 2.3.6 [flutter plugin_platform_interface vector_math meta] - geolocator_web 2.0.6 [flutter flutter_web_plugins geolocator_platform_interface] - google_maps_flutter_platform_interface 2.1.3 [collection flutter meta plugin_platform_interface stream_transform] - google_sign_in_platform_interface 2.1.0 [flutter meta quiver] - google_sign_in_web 0.10.0+3 [flutter flutter_web_plugins google_sign_in_platform_interface js meta] - graphs 2.1.0 [collection] - html 0.15.0 [csslib source_span] - http_client_helper 2.0.2 [http] - http_parser 4.0.0 [charcode collection source_span string_scanner typed_data] - image 3.0.8 [archive meta xml] - in_app_review_platform_interface 2.0.2 [flutter url_launcher plugin_platform_interface platform] - js 0.6.3 - lints 1.0.1 - logger 1.1.0 - matcher 0.12.10 [stack_trace] - meta 1.7.0 - mime 1.0.1 - nested 1.0.0 [flutter] - nm 0.3.0 [dbus] - octo_image 1.0.0+1 [flutter flutter_blurhash] - path_drawing 0.5.1+1 [vector_math meta path_parsing flutter] - path_parsing 0.2.1 [vector_math meta] - path_provider_linux 2.1.0 [flutter path path_provider_platform_interface xdg_directories] - path_provider_macos 2.0.2 [flutter] - path_provider_platform_interface 2.0.1 [flutter meta platform plugin_platform_interface] - path_provider_windows 2.0.3 [ffi flutter meta path path_provider_platform_interface win32] - pedantic 1.11.1 - permission_handler_platform_interface 3.7.0 [flutter meta plugin_platform_interface] - petitparser 4.4.0 [meta] - platform 3.0.2 - plugin_platform_interface 2.0.2 [meta] - process 4.2.4 [file path platform] - quiver 3.0.1+1 [matcher] - recase 4.0.0 - rxdart 0.27.2 - share_plus_linux 2.0.4 [share_plus_platform_interface file flutter meta url_launcher] - share_plus_macos 2.0.2 [share_plus_platform_interface flutter] - share_plus_platform_interface 2.0.1 [flutter meta mime plugin_platform_interface] - share_plus_web 2.0.4 [share_plus_platform_interface url_launcher flutter flutter_web_plugins meta] - share_plus_windows 2.0.3 [share_plus_platform_interface flutter meta url_launcher] - shared_preferences_linux 2.0.2 [file meta flutter path path_provider_linux shared_preferences_platform_interface] - shared_preferences_macos 2.0.2 [flutter shared_preferences_platform_interface] - shared_preferences_platform_interface 2.0.0 [flutter] - shared_preferences_web 2.0.2 [flutter flutter_web_plugins meta shared_preferences_platform_interface] - shared_preferences_windows 2.0.2 [flutter file meta path path_provider_platform_interface path_provider_windows shared_preferences_platform_interface] - sky_engine 0.0.99 - source_span 1.8.1 [collection path term_glyph] - sqflite_common 2.0.1+1 [synchronized path meta] - stack_trace 1.10.0 [path] - stream_channel 2.1.0 [async] - stream_transform 2.0.0 - string_scanner 1.1.0 [charcode source_span] - synchronized 3.0.0 - term_glyph 1.2.0 - test_api 0.4.2 [async boolean_selector collection meta source_span stack_trace stream_channel string_scanner term_glyph matcher] - typed_data 1.3.0 [collection] - universal_platform 1.0.0+1 - url_launcher_linux 2.0.2 [flutter] - url_launcher_macos 2.0.2 [flutter] - url_launcher_platform_interface 2.0.4 [flutter plugin_platform_interface] - url_launcher_web 2.0.4 [flutter flutter_web_plugins meta url_launcher_platform_interface] - url_launcher_windows 2.0.2 [flutter] - vector_math 2.1.0 - video_player_platform_interface 4.2.0 [flutter flutter_test meta] - video_player_web 2.0.4 [flutter flutter_web_plugins meta video_player_platform_interface] - webview_flutter_android 2.2.1 [flutter webview_flutter_platform_interface] - webview_flutter_platform_interface 1.4.0 [flutter plugin_platform_interface] - webview_flutter_wkwebview 2.2.0 [flutter webview_flutter_platform_interface] - win32 2.2.10 [ffi] - xdg_directories 0.2.0 [meta path process] - xml 5.3.1 [collection meta petitparser] - yaml 3.1.0 [collection source_span string_scanner] ```

firebase / flutterfire