code: public String getGroupId() {
      if (group == null ) {
        return null;
      } else {
        return group.id == null ? group.nsid : group.id;
      }
    }
docs: This parameter is set by the methods {@link net.jeremybrooks.jinx.api.UrlsApi#lookupGroup(String)} and
  {@link net.jeremybrooks.jinx.api.UrlsApi#getGroup(String)}
  
  @return the group id, AKA NSID.