no group below lollipop

Examples/simple-fcm-client/app/App.js

@@ -67,6 +67,7 @@ export default class App extends Component {
       sound: "bell.mp3",
       large_icon: "https://image.freepik.com/free-icon/small-boy-cartoon_318-38077.jpg",
       show_in_foreground: true,
+      group: 'test',
       number: 10
     });
   }

android/src/main/java/com/evollu/react/fcm/SendNotificationTask.java

@@ -70,9 +70,12 @@ public class SendNotificationTask extends AsyncTask<Void, Void, Void> {
             .setAutoCancel(bundle.getBoolean("auto_cancel", true))
             .setNumber((int)bundle.getDouble("number"))
             .setSubText(bundle.getString("sub_text"))
-            .setGroup(bundle.getString("group"))
             .setVibrate(new long[]{0, DEFAULT_VIBRATION})
             .setExtras(bundle.getBundle("data"));
+
+            if(android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP){
+                notification.setGroup(bundle.getString("group"));
+            }
             
             if (bundle.containsKey("ongoing") && bundle.getBoolean("ongoing")) {
                 notification.setOngoing(bundle.getBoolean("ongoing"));