* @return The appropriate sort builder for the field.
     */
    protected SortBuilder<?> createFieldSortBuilder(final String field, final SortOrder order) {
        if (QueryFieldConfig.SCORE_FIELD.equals(field) || QueryFieldConfig.DOC_SCORE_FIELD.equals(field)) {
            return SortBuilders.scoreSort().order(order);
        }
        return SortBuilders.fieldSort(field).order(order);
    }

    /**