* The value is, e.g. true <br>
     * comment: Whether to append data to documents.
     * @return The determination, true or false. (if not found, exception but basically no way)
     */
    boolean isCrawlerDocumentAppendData();

    /**
     * Get the value for the key 'crawler.document.append.filename'. <br>
     * The value is, e.g. false <br>
     * comment: Whether to append filename to documents.