code: public Optional<SingularityRequestGroup> saveRequestGroup(SingularityRequestGroup requestGroup) {
      final Function<String, String> requestUri = (host) -> String.format(REQUEST_GROUPS_FORMAT, getApiBase(host));
  
      return post(requestUri, "request group", Optional.of(requestGroup), Optional.of(SingularityRequestGroup.class));
    }
docs: Update or add a {@link SingularityRequestGroup}
  
  @param requestGroup
  The request group to update or add
  
  @return
  A {@link SingularityRequestGroup} if the update was successful