sortFieldSet = new HashSet<>();
            Collections.addAll(sortFieldSet, sortFields);
        }
        if (apiResponseFieldSet == null) {
            setApiResponseFields(fessConfig.getQueryAdditionalApiResponseFields(//
                    SCORE_SORT_VALUE, //
                    fessConfig.getResponseFieldContentDescription(), //
                    fessConfig.getResponseFieldContentTitle(), //

    }

    String getQueryAdditionalApiResponseFields();

    default String[] getQueryAdditionalApiResponseFields(final String... fields) {
        final List<String> list = new ArrayList<>(fields.length + 10);
        stream(fields).of(stream -> stream.forEach(list::add));
        split(getQueryAdditionalApiResponseFields(), ",")

     * comment: Additional API response fields for queries.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getQueryAdditionalApiResponseFields();

    /**
     * Get the value for the key 'query.additional.api.response.fields' as {@link Integer}. <br>
     * The value is, e.g.  <br>
     * comment: Additional API response fields for queries.