@Override
    public void cacheGroupsAdd(List<String> groups) throws IOException {
    }
Wrapper around Hadoop's MiniKdc for use in hive tests.
Has functions to manager users and their keytabs. This includes a hive service principal,
a superuser principal for testing proxy user privilegs.
Has a set of default users that it initializes.
See hive-minikdc/src/test/resources/core-site.xml for users granted proxy user privileges.
itests/hive-minikdc/src/test/java/org/apache/hive/minikdc/MiniHiveKdc.java