@Override
 public void onError(Session session, OpentokError error) {
   mCallback.onTokBoxError(new Exception(error.getMessage()));
 }
 @Override
 public void onError(PublisherKit publisherKit, OpentokError opentokError) {
   Log.i(LOGTAG, "Publisher exception: " + opentokError.getMessage());
 }
 @Override
 public void onError(PublisherKit publisher, OpentokError error) {
   mCallback.onTokBoxError(new Exception(error.getMessage()));
 }