FormField formField = dataForm.addField();
formField.setVariable("FORM_TYPE");
formField.setType(FormField.Type.hidden);
formField.addValue("http://jabber.org/protocol/pubsub#subscribe_options");
formField = dataForm.addField();
formField.setVariable("pubsub#subscription_type");
formField.addValue("items");
formField = dataForm.addField();
formField.setVariable("pubsub#subscription_depth");