* Also updates the sortFieldSet for O(1) lookup performance.
     *
     * @param sortFields array of field names that can be used for sorting
     */
    public void setSortFields(final String[] sortFields) {
        this.sortFields = sortFields;
        sortFieldSet = new HashSet<>();
        Collections.addAll(sortFieldSet, sortFields);
    }

     * Test that setting sort fields creates both array and Set.
     */
    @Test
    public void test_setSortFields_createsSet() {
        String[] fields = { "sort1", "sort2", "sort3" };
        queryFieldConfig.setSortFields(fields);

        // Verify array is set
        assertNotNull(queryFieldConfig.sortFields);
        assertSame(fields, queryFieldConfig.sortFields);
        assertEquals(3, queryFieldConfig.sortFields.length);

        String[] fields = { "sort1", "sort2", "sort3" };
        queryFieldConfig.setSortFields(fields);

        String[] result = queryFieldConfig.getSortFields();
        assertSame(fields, result);
    }

    @Test
    public void test_setSortFields() {
        String[] fields = { "sort1", "sort2", "sort3" };
        queryFieldConfig.setSortFields(fields);

        assertSame(fields, queryFieldConfig.sortFields);
    }