presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/thrift/ThriftHiveMetastoreClient.java/ThriftHiveMetastoreClient/getDelegationToken
class ThriftHiveMetastoreClient:    @Override
    public String getDelegationToken(String userName)
            throws TException
    {
        return client.get_delegation_token(userName, userName);
    }