code: void notifyOmemoMucMessageReceived(MultiUserChat muc,
                                         Stanza stanza,
                                         OmemoMessage.Received decryptedMessage) {
          for (OmemoMucMessageListener l : omemoMucMessageListeners) {
              l.onOmemoMucMessageReceived(muc, stanza, decryptedMessage);
          }
      }
docs: Notify all registered OmemoMucMessageListeners of an incoming OmemoMessageElement in a MUC.
  
  @param muc               MultiUserChat the message was received in.
  @param stanza            Original Stanza.
  @param decryptedMessage  Decrypted OmemoMessage.