docs: public void sendCancelledNotification(Jid to, String packetID) throws NotConnectedException, InterruptedException {
          // Create the message to send
          Message msg = new Message(to);
          // Create a MessageEvent Package and add it to the message
          MessageEvent messageEvent = new MessageEvent();
          messageEvent.setCancelled(true);
          messageEvent.setStanzaId(packetID);
          msg.addExtension(messageEvent);
          // Send the packet
          connection().sendStanza(msg);
      }