code: public CustomAttribute changeCustomAttribute(final Object userIdOrUsername, final String key, final String value) throws GitLabApiException {
          return createCustomAttribute(userIdOrUsername, key, value);
      }
docs: Changes custom attribute for the given user
  
  @param userIdOrUsername the user in the form of an Integer(ID), String(username), or User instance
  @param key    for the customAttribute
  @param value  for the customAttribute
  @return changedCustomAttribute
  @throws GitLabApiException on failure while changing customAttributes