code: public Collection<SingularityRequestGroup> getRequestGroups() {
      final Function<String, String> requestUri = (host) -> String.format(REQUEST_GROUPS_FORMAT, getApiBase(host));
  
      return getCollection(requestUri, "request groups", REQUEST_GROUP_COLLECTION);
    }
docs: Retrieve the list of request groups
  
  @return
  A collection of {@link SingularityRequestGroup}