code: public String getUserId() {
      if (user == null) {
        return null;
      } else {
        return user.id == null ? user.nsid : user.id;
      }
    }
docs: This parameter is set by the method {@link net.jeremybrooks.jinx.api.UrlsApi#lookupUser(String)},
  {@link net.jeremybrooks.jinx.api.UrlsApi#getUserPhotos(String)} and
  {@link net.jeremybrooks.jinx.api.UrlsApi#getUserProfile(String)}.
  
  @return the user id, AKD NSID.