docs: public void requestVoice() throws NotConnectedException, InterruptedException {
          DataForm form = new DataForm(DataForm.Type.submit);
          FormField formTypeField = new FormField(FormField.FORM_TYPE);
          formTypeField.addValue(MUCInitialPresence.NAMESPACE + "#request");
          form.addField(formTypeField);
          FormField requestVoiceField = new FormField("muc#role");
          requestVoiceField.setType(FormField.Type.text_single);
          requestVoiceField.setLabel("Requested role");
          requestVoiceField.addValue("participant");
          form.addField(requestVoiceField);
          Message message = new Message(room);
          message.addExtension(form);
          connection.sendStanza(message);
      }