/** The key of the configuration. e.g. default */
    String search_engine_TYPE = "search_engine.type";

    /** The key of the configuration. e.g. http://localhost:9201 */
    String search_engine_HTTP_URL = "search_engine.http.url";

    /** The key of the configuration. e.g.  */
    String search_engine_HTTP_SSL_certificate_authorities = "search_engine.http.ssl.certificate_authorities";

    /** The key of the configuration. e.g.  */