public void test_encodeUrl_unicode() {
        assertEquals("%3F", DocumentUtil.encodeUrl("あ"));
        assertEquals("%3F%3F%3F", DocumentUtil.encodeUrl("あいう"));
    }

    @Test
    public void test_complex_document_structure() {
        Map<String, Object> doc = new HashMap<>();

        Map<String, Object> nestedMap = new HashMap<>();
        nestedMap.put("nestedKey", "nestedValue");
        doc.put("nested", nestedMap);