}

        // Test negative cases
        assertFalse(queryFieldConfig.isFacetField("nonexistent"));
        assertFalse(queryFieldConfig.isFacetField("title"));
        // Blank fields are handled before Set lookup
        assertFalse(queryFieldConfig.isFacetField(""));
        assertFalse(queryFieldConfig.isFacetField(null));

     * 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);
    }

    /**

        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(""));

            stream(facetInfo.field).of(stream -> stream.forEach(f -> {
                if (!queryFieldConfig.isFacetField(f)) {
                    throw new SearchQueryException("Invalid facet field: " + f);
                }
                final String encodedField = BaseEncoding.base64().encode(f.getBytes(StandardCharsets.UTF_8));