protected synchronized void update(final String md5, final long lastModifyTime) {
        this.md5 = md5;
        this.lastModifyTime = lastModifyTime;
    }
@Test
    public void testUpdate() {
        String group = "default";
        String json = "{\"name\":\"shenyu\"}";
        String md51 = "8e8a3a2fdbd4368f169aa88c5fdce5a1";
        ConfigDataCache cache = new ConfigDataCache(group, json, md51, 0);
        assertEquals(cache.getMd5(), md51);
        assertEquals(cache.getJson(), json);
        assertEquals(cache.getGroup(), group);
        String md52 = "8e8a3a2fdbd4368f169aa88c5fdce5au";
        cache.update(md52, 1);
        assertEquals(cache.getMd5(), md52);
        assertEquals(cache.getLastModifyTime(), 1);
    }