final ExtractData extractData = getExtractData(extractor, in, createExtractParams(responseData, crawlingConfig));
            content = extractData.getContent();
            if (fessConfig.isCrawlerDocumentFileIgnoreEmptyContent() && StringUtil.isBlank(content)) {
                return null;
            }
            if (getLogger().isDebugEnabled()) {
                getLogger().debug("ExtractData: {}", extractData);

     * comment: Whether to ignore files with empty content.
     * @return The determination, true or false. (if not found, exception but basically no way)
     */
    boolean isCrawlerDocumentFileIgnoreEmptyContent();

    /**
     * Get the value for the key 'crawler.document.file.max.title.length'. <br>
     * The value is, e.g. 100 <br>
     * comment: Maximum length of file title in documents.