public void onNotify(JID jid, String id) {
    Contact contact = ContactList.getInstance().get(jid).orElse(null);
    if (contact == null) {
      LOGGER.warning("can't find contact with jid:" + jid);
      return;
    }

    if (id.isEmpty()) {
      // contact disabled avatar publishing
      // TODO
    }

    Avatar avatar = contact.getAvatar().orElse(null);
    if (avatar != null && avatar.id.equals(id))
      // avatar is not new
      return;

    mClient.requestAvatar(jid, id);
  }