public static final String USER_CODE = "userCode";

    /** Search query field name for logging. */
    public static final String SEARCH_FIELD_LOG_SEARCH_QUERY = "q";

    /** Statistics report type parameter name. */
    public static final String STATS_REPORT_TYPE = "reportType";

    /** Result document ID cache key. */
    public static final String RESULT_DOC_ID_CACHE = "resultDocIds";

        public ApiResult result() {
            return new ApiResult(this);
        }
    }

    /**
     * Represents an API response containing statistical information.
     */
    public static class ApiStatsResponse extends ApiResponse {
        /** The statistical data. */
        protected Map<String, Object> stats;

        /**
         * Default constructor for ApiStatsResponse.
         */