/**
     * Default constructor.
     */
    public SearchEngineClient() {
        // Default constructor
    }

    private static final Logger logger = LogManager.getLogger(SearchEngineClient.class);

    private static final String DOC_INDEX = "fess";

    private static final String LOG_INDEX_PREFIX = "fess_log";

    private static final String USER_INDEX_PREFIX = "fess_user";