map.put("aaa", "111");
        map.put("aaaBbb", "222");
        map.put("aaaBbbCcc", "333");
        map.put("ccc.ddd", "444");
        return new ParamMap<>(map);
    }

    @Test
    public void test_snake_get() {
        Map<Object, Object> paramMap = createSnakeMap();

        assertNull(paramMap.get("xxx"));
        assertEquals("111", paramMap.get("aaa"));
        assertEquals("222", paramMap.get("aaa_bbb"));