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**Description**

Related to the discussion here: https://github.com/apache/airflow/pull/8553#discussion_r416136954

Allow user to define expected terminal state. e.g. `JOB_STATE_CANCELLED` could be not treated as failure but expected terminal state.


<!-- A short description of your feature -->


"""
    Stops the job with the specified name prefix or Job ID.
    All jobs with provided name prefix will be stopped.
    Streaming jobs are drained by default.
    Parameter ``job_name_prefix`` and ``job_id`` are mutually exclusive.
    .. seealso::
        For more details on stopping a pipeline see:
        https://cloud.google.com/dataflow/docs/guides/stopping-a-pipeline
    .. seealso::
        For more information on how to use this operator, take a look at the guide:
        :ref:`howto/operator:DataflowStopJobOperator`
    :param job_name_prefix: Name prefix specifying which jobs are to be stopped.
    :param job_id: Job ID specifying which jobs are to be stopped.
    :param project_id: Optional, the Google Cloud project ID in which to start a job.
        If set to None or missing, the default project_id from the Google Cloud connection is used.
    :param location: Optional, Job location. If set to None or missing, "us-central1" will be used.
    :param gcp_conn_id: The connection ID to use connecting to Google Cloud.
    :param poll_sleep: The time in seconds to sleep between polling Google
        Cloud Platform for the dataflow job status to confirm it's stopped.
    :param impersonation_chain: Optional service account to impersonate using short-term
        credentials, or chained list of accounts required to get the access_token
        of the last account in the list, which will be impersonated in the request.
        If set as a string, the account must grant the originating account
        the Service Account Token Creator IAM role.
        If set as a sequence, the identities from the list must grant
        Service Account Token Creator IAM role to the directly preceding identity, with first