if (logger.isDebugEnabled()) {
            logger.debug("Sending {} documents to a server.", docList.size());
        }
        try {
            if (fessConfig.isThumbnailCrawlerEnabled()) {
                final ThumbnailManager thumbnailManager = ComponentUtil.getThumbnailManager();
                final String thumbnailField = fessConfig.getIndexFieldThumbnail();

     * The value is, e.g. true <br>
     * @return The determination, true or false. (if not found, exception but basically no way)
     */
    boolean isThumbnailCrawlerEnabled();

    /**
     * Get the value for the key 'thumbnail.system.monitor.interval'. <br>
     * The value is, e.g. 60 <br>