presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/thrift/ThriftMetastoreUtil.java/ThriftMetastoreUtil/listEnabledPrincipals
class ThriftMetastoreUtil:    public static Stream<HivePrincipal> listEnabledPrincipals(SemiTransactionalHiveMetastore metastore, ConnectorIdentity identity)
    {
        return Stream.concat(
                Stream.of(new HivePrincipal(USER, identity.getUser())),
                listEnabledRoles(identity, metastore::listRoleGrants)
                        .map(role -> new HivePrincipal(ROLE, role)));
    }