Training with a custom service account needs a new field named service account
trainingInput:
  serviceAccount: CUSTOM_SERVICE_ACCOUNT

https://cloud.google.com/ai-platform/training/docs/custom-service-account


tests/providers/google/cloud/operators/test_mlengine.py
task = MLEngineManageModelOperator(
            task_id="task-id",
            project_id=TEST_PROJECT_ID,
            model=TEST_MODEL,
            operation="invalid",
            gcp_conn_id=TEST_GCP_CONN_ID,
            delegate_to=TEST_DELEGATE_TO,
        )
        with self.assertRaises(ValueError):
            task.execute(None)
class TestMLEngineCreateModelOperator(unittest.TestCase):