
**Apache Airflow version**:

master

**What happened**:

https://github.com/apache/airflow/blob/master/airflow/models/baseoperator.py#L356 --> should be timedelta not datetime


tests/serialization/test_dag_serialization.py
"""
        Additional Properties are disabled on DAGs. This test verifies that all the
        keys in DAG.get_serialized_fields are listed in Schema definition.
        """
        dag_schema: dict = load_dag_schema_dict()["definitions"]["dag"]["properties"]
        
        ignored_keys: set = {"is_subdag", "tasks", "has_on_success_callback", "has_on_failure_callback"}
        dag_params: set = set(dag_schema.keys()) - ignored_keys
        assert set(DAG.get_serialized_fields()) == dag_params
    def test_operator_subclass_changing_base_defaults(self):
        assert (
            BaseOperator(task_id='dummy').do_xcom_push is True
        ), "Precondition check! If this fails the test won't make sense"
        class MyOperator(BaseOperator):
            def __init__(self, do_xcom_push=False, **kwargs):
                super().__init__(**kwargs)
                self.do_xcom_push = do_xcom_push
        op = MyOperator(task_id='dummy')
        assert op.do_xcom_push is False
        blob = SerializedBaseOperator.serialize_operator(op)
        serialized_op = SerializedBaseOperator.deserialize_operator(blob)
        assert serialized_op.do_xcom_push is False
    def test_no_new_fields_added_to_base_operator(self):