docs: public Subscription subscribe(String jid, SubscribeForm subForm) throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
          PubSub request = createPubsubPacket(Type.set, new SubscribeExtension(jid, getId()));
          request.addExtension(new FormNode(FormNodeType.OPTIONS, subForm));
          PubSub reply = sendPubsubPacket(request);
          return reply.getExtension(PubSubElementType.SUBSCRIPTION);
      }