**Description**

The operator is arguably unnecessarily limited to AI Platform’s standard images. The only change that is required to lift this constraint is making `package_uris` and `training_python_module` optional with default values `[]` and `None`, respectively. Then, using `master_config`, one can supply `imageUri` and run any image of choice.

**Use case / motivation**

This will open up for running arbitrary images on AI Platform.

**Are you willing to submit a PR?**

If the above sounds reasonable, I can open pull requests.
airflow/providers/google/cloud/operators/mlengine.py
if not self._model_name:
            raise AirflowException("The model_name parameter could not be empty.")
        if not self._version:
            raise AirflowException("The version parameter could not be empty.")
    def execute(self, context):
        hook = MLEngineHook(
            gcp_conn_id=self._gcp_conn_id,
            delegate_to=self._delegate_to,
            impersonation_chain=self._impersonation_chain,
        )
        return hook.create_version(
            project_id=self._project_id, model_name=self._model_name, version_spec=self._version
        )
class MLEngineSetDefaultVersionOperator(BaseOperator):