public static String getKey(String dataId, String group) {
        return getKey(dataId, group, "");
    }
@Test
    public void testGetKey1() {
        String[] strings = {"dataId", "group", "datumStr"};
        String expected = "dataId+group+datumStr";
        String key = GroupKey.getKey(strings);
        Assert.isTrue(key.equals(expected));
    }