assertNull(DocumentUtil.getValue(null, "key", String.class));
        assertNull(DocumentUtil.getValue(null, "key", Integer.class));
    }

    @Test
    public void test_getValue_with_null_key() {
        Map<String, Object> doc = new HashMap<>();
        doc.put("key", "value");
        assertNull(DocumentUtil.getValue(doc, null, String.class));