doc.put("key", null);
        assertEquals("default", DocumentUtil.getValue(doc, "key", String.class, "default"));
    }

    @Test
    public void test_list_with_null_elements() {
        Map<String, Object> doc = new HashMap<>();
        List<String> listWithNulls = Arrays.asList("a", null, "b", null, "c");
        doc.put("key", listWithNulls);