title: Missing default Notification Channel metadata in AndroidManifest in Flutter
body: <p>I am using <code>firebase_messaging: ^5.0.1</code> package to achieve push notifications, everything is working fine in IOS whereas coming to the android when my mobile application running background I am receiving a notification but it is not navigating to the respective screens, it just opens the default screen. How to achieve navigation to that particular screen.</p>
  
  <p>PS: I implemented click_action functionality that's the reason it's working fine in iOS but Android it shows the below message </p>
  
  <p><code>W/FirebaseMessaging( 8260): Missing Default Notification Channel metadata in AndroidManifest. Default value will be used.</code></p>
  
  <p>Here is my AndroidManifest:</p>
  
  <pre><code>&lt;manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.example.check"&gt;
  
      &lt;!-- io.flutter.app.FlutterApplication is an android.app.Application that
           calls FlutterMain.startInitialization(this); in its onCreate method.
           In most cases you can leave this as-is, but you if you want to provide
           additional functionality it is fine to subclass or reimplement
           FlutterApplication and put your custom class here. --&gt;
      &lt;application
          android:name="io.flutter.app.FlutterApplication"
          android:label="Cargill FC"
          android:icon="@mipmap/ic_launcher"&gt;
          &lt;activity
              android:name=".MainActivity"
              android:launchMode="singleTop"
              android:theme="@style/LaunchTheme"
              android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
              android:hardwareAccelerated="true"
              android:allowBackup="false"
              android:fullBackupContent="false"
              android:windowSoftInputMode="adjustResize"&gt;
              &lt;!-- This keeps the window background of the activity showing
                   until Flutter renders its first frame. It can be removed if
                   there is no splash screen (such as the default splash screen
                   defined in @style/LaunchTheme). --&gt;
              &lt;meta-data
                  android:name="io.flutter.app.android.SplashScreenUntilFirstFrame"
                  android:value="true" /&gt;
              &lt;intent-filter&gt;
                  &lt;action android:name="android.intent.action.MAIN"/&gt;
                  &lt;category android:name="android.intent.category.LAUNCHER"/&gt;
              &lt;/intent-filter&gt;
              &lt;intent-filter&gt;
                  &lt;action android:name="FLUTTER_NOTIFICATION_CLICK" /&gt;
                  &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
              &lt;/intent-filter&gt;
          &lt;/activity&gt;
      &lt;/application&gt;
  &lt;/manifest&gt;
  </code></pre>
  
  <p>Push notificatio code:</p>
  
  <pre><code>@override
    void initState() {
      super.initState();
      tabController = new TabController(length: 2, vsync: this);
  
      _firebaseMessaging.configure(
        onMessage: (Map&lt;String, dynamic&gt; message) async {
          onFirebaseMessage(message);
        },
        onLaunch: (Map&lt;String, dynamic&gt; message) async {
          print("onLaunch: $message");
        },
        onResume: (Map&lt;String, dynamic&gt; message) async {
          print("onResume: $message");
        },
      );
  
      _firebaseMessaging.requestNotificationPermissions(const IosNotificationSettings(sound: true, badge: true, alert: true));
      _firebaseMessaging.onIosSettingsRegistered.listen((IosNotificationSettings settings) {
        print("Settings registered: $settings");
      });
  
      _firebaseMessaging.getToken().then(registerFirebaseTokenForUser);
    }
  </code></pre>
  
  <p>Here onMessage is the only thing working perfectly in Android. I want to achieve the same when it is running background.</p>