Put the data into the data key for Android

Before this change the elements in the data object are put into the main json object.  The docs say that this should be underneath the data key.  This causes an issue with TypeScript because you're not able to access keys not defined in the interface.

Author: Blake Peterman

platforms/android/firebase-release.aar

@@ -17,19 +17,21 @@ public class MyFirebaseMessagingService extends FirebaseMessagingService {
   public void onMessageReceived(RemoteMessage remoteMessage) {
     try {
       final JSONObject json = new JSONObject()
-        .put("foreground", true)
-        .put("from", remoteMessage.getFrom());
+              .put("foreground", true)
+              .put("from", remoteMessage.getFrom());
 
       final RemoteMessage.Notification not = remoteMessage.getNotification();
       if (not != null) {
         json.put("title", not.getTitle())
-          .put("body", not.getBody());
+                .put("body", not.getBody());
       }
 
       final Map<String, String> data = remoteMessage.getData();
+      final JSONObject data_json = new JSONObject();
       for (Map.Entry<String, String> stringStringEntry : data.entrySet()) {
-        json.put(stringStringEntry.getKey(), stringStringEntry.getValue());
+        data_json.put(stringStringEntry.getKey(), stringStringEntry.getValue());
       }
+      json.put("data", data_json);
 
       FirebasePlugin.executeOnNotificationReceivedCallback(json.toString());
     } catch (JSONException e) {
@@ -62,4 +64,4 @@ private void sendNotification(String messageBody) {
   }
 */
 
-}
+}