}
    }

    /**
     * Flushes configuration files to the search engine and executes a callback.
     *
     * @param callback the callback to execute after flushing
     */
    public void flushConfigFiles(final Runnable callback) {
        final FessConfig fessConfig = ComponentUtil.getFessConfig();

        final String fesenType = fessConfig.getFesenType();
        switch (fesenType) {