if (url == null) {
            return null;
        }

        final FessConfig fessConfig = getFessConfig();
        String enc = Constants.UTF_8;
        if (StringUtil.isBlank(fessConfig.getCrawlerDocumentFileNameEncoding())) {
            final UrlQueue<?> urlQueue = CrawlingParameterUtil.getUrlQueue();
            if (urlQueue != null) {
                final String parentUrl = urlQueue.getParentUrl();

     * The value is, e.g.  <br>
     * comment: Encoding for file names in documents.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getCrawlerDocumentFileNameEncoding();

    /**
     * Get the value for the key 'crawler.document.file.name.encoding' as {@link Integer}. <br>
     * The value is, e.g.  <br>
     * comment: Encoding for file names in documents.