* Uses O(1) Set lookup for improved performance.
     *
     * @param field the field name to check
     * @return true if the field can be used for faceted search, false otherwise
     */
    public boolean isFacetField(final String field) {
        if (StringUtil.isBlank(field)) {
            return false;
        }
        return facetFieldSet != null && facetFieldSet.contains(field);
    }

    /**