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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 -->


def setup_method(self):
        self.dataflow = DataflowCreatePythonJobOperator(
            task_id=TASK_ID,
            py_file=PY_FILE,
            job_name=JOB_NAME,
            py_options=PY_OPTIONS,
            dataflow_default_options=DEFAULT_OPTIONS_PYTHON,
            options=ADDITIONAL_OPTIONS,
            poll_sleep=POLL_SLEEP,
            location=TEST_LOCATION,
        )
        self.expected_airflow_version = "v" + airflow.version.version.replace(".", "-").replace("+", "-")
    def test_init(self):
        """Test DataflowCreatePythonJobOperator instance is properly initialized."""
        assert self.dataflow.task_id == TASK_ID
        assert self.dataflow.job_name == JOB_NAME
        assert self.dataflow.py_file == PY_FILE
        assert self.dataflow.py_options == PY_OPTIONS
        assert self.dataflow.py_interpreter == PY_INTERPRETER
        assert self.dataflow.poll_sleep == POLL_SLEEP
        assert self.dataflow.dataflow_default_options == DEFAULT_OPTIONS_PYTHON
        assert self.dataflow.options == EXPECTED_ADDITIONAL_OPTIONS
    @mock.patch(
        "airflow.providers.google.cloud.operators.dataflow.process_line_and_extract_dataflow_job_id_callback"
    )
    @mock.patch("airflow.providers.google.cloud.operators.dataflow.BeamHook")
    @mock.patch("airflow.providers.google.cloud.operators.dataflow.DataflowHook")
    @mock.patch("airflow.providers.google.cloud.operators.dataflow.GCSHook")
    def test_exec(self, gcs_hook, dataflow_hook_mock, beam_hook_mock, mock_callback_on_job_id):