docs: public CustomAttribute changeCustomAttribute(final Object userIdOrUsername, final CustomAttribute customAttribute) throws GitLabApiException {
  
          if (Objects.isNull(customAttribute)) {
              throw new IllegalArgumentException("CustomAttributes can't be null");
          }
  
          //changing & creating custom attributes is the same call in gitlab api
          // -> https://docs.gitlab.com/ce/api/custom_attributes.html#set-custom-attribute
          return createCustomAttribute(userIdOrUsername, customAttribute.getKey(), customAttribute.getValue());
      }