public function getRoleByKey(string $key)
    {
        if (strlen($key) === 0) {
            throw new ENabuCoreException(
                ENabuCoreException::ERROR_UNEXPECTED_PARAM_VALUE,
                array('$key', print_r($key, true))
            );
        }

        return $this->nb_role_list->getItem($key, CNabuRoleList::INDEX_KEY);
    }