@darshan-majithiya had opened #15429 to add the hyperparameter tuning PR but it's gone stale. I'm adding this issue to see if they want to pick it back up, or if not, if someone wants to pick up where they left off in the spirit of open source 😄 
airflow/providers/google/cloud/operators/mlengine.py
"""
    Operator for launching a MLEngine training job.
    .. seealso::
        For more information on how to use this operator, take a look at the guide:
        :ref:`howto/operator:MLEngineStartTrainingJobOperator`
    :param job_id: A unique templated id for the submitted Google MLEngine
        training job. (templated)
    :type job_id: str
    :param region: The Google Compute Engine region to run the MLEngine training
        job in (templated).
    :type region: str
    :param package_uris: A list of Python package locations for the training
        job, which should include the main training program and any additional
        dependencies. This is mutually exclusive with a custom image specified
        via master_config. (templated)
    :type package_uris: List[str]
    :param training_python_module: The name of the Python module to run within
        the training job after installing the packages. This is mutually
        exclusive with a custom image specified via master_config. (templated)
    :type training_python_module: str