/** The key of the configuration. e.g. 0 */
    String QUERY_HIGHLIGHT_NO_MATCH_SIZE = "query.highlight.no.match.size";

    /** The key of the configuration. e.g. score */
    String QUERY_HIGHLIGHT_ORDER = "query.highlight.order";

    /** The key of the configuration. e.g. 256 */
    String QUERY_HIGHLIGHT_PHRASE_LIMIT = "query.highlight.phrase.limit";

    /** The key of the configuration. e.g. hl_content,digest */