**Describe the solution you'd like**

An option to make the `IDENTIFIED WITH` section mandatory.

const Poco::Util::AbstractConfiguration & config,
    const String & key,
    const String & config_dir,
    const String & dbms_dir,
    const String & include_from_path,
    const zkutil::GetZooKeeper & get_zookeeper_function)
{
    Strings keys_in_user_directories;
    config.keys(key, keys_in_user_directories);
    for (const String & key_in_user_directories : keys_in_user_directories)
    {
        String prefix = key + "." + key_in_user_directories;
        String type = key_in_user_directories;
        if (size_t bracket_pos = type.find('['); bracket_pos != String::npos)
            type.resize(bracket_pos);
        if ((type == "users_xml") || (type == "users_config"))
            type = UsersConfigAccessStorage::STORAGE_TYPE;
        else if ((type == "local") || (type == "local_directory"))
            type = DiskAccessStorage::STORAGE_TYPE;
        else if (type == "ldap")
            type = LDAPAccessStorage::STORAGE_TYPE;
        String name = config.getString(prefix + ".name", type);
        if (type == MemoryAccessStorage::STORAGE_TYPE)
        {
            bool allow_backup = config.getBool(prefix + ".allow_backup", true);
            addMemoryStorage(name, allow_backup);
        }