assertTrue(queryFieldConfig.isFacetField("category"));
        assertTrue(queryFieldConfig.isFacetField("type"));
        assertTrue(queryFieldConfig.isFacetField("author"));
        assertTrue(queryFieldConfig.isFacetField("date"));

        // Test invalid facet fields
        assertFalse(queryFieldConfig.isFacetField("invalid"));
        assertFalse(queryFieldConfig.isFacetField(""));

     *
     * @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;
        }
        boolean flag = false;
        for (final String f : facetFields) {
            if (field.equals(f)) {