/** The key of the configuration. e.g. groovy */
    String CRAWLER_DEFAULT_SCRIPT = "crawler.default.script";

    /** The key of the configuration. e.g. 0 */
    String CRAWLER_HTTP_thread_pool_SIZE = "crawler.http.thread_pool.size";

    /** The key of the configuration. e.g. 100 */
    String CRAWLER_DOCUMENT_MAX_SITE_LENGTH = "crawler.document.max.site.length";

    /** The key of the configuration. e.g. UTF-8 */