@Override
    protected HiveMetastoreAuthenticationProvider initialValue() {
      try {
        return  (HiveMetastoreAuthenticationProvider) HiveUtils.getAuthenticator(
            tConfig.get(), HiveConf.ConfVars.HIVE_METASTORE_AUTHENTICATOR_MANAGER);
      } catch (HiveException he) {
        throw new IllegalStateException("Authentication provider instantiation failure",he);
      }
    }
AuthorizationPreEventListener : A MetaStorePreEventListener that
performs authorization/authentication checks on the metastore-side.

Note that this can only perform authorization checks on defined
metastore PreEventContexts, such as the adding/dropping and altering
of databases, tables and partitions.
ql/src/java/org/apache/hadoop/hive/ql/security/authorization/AuthorizationPreEventListener.java