Used by Variable/Connection.

https://github.com/apache/airflow/blob/894741e311ffd642e036b80d3b1b5d53c3747cad/airflow/secrets/metastore.py#L32

"""Populate operator attributes with serialized values.
        This covers simple attributes that don't reference other things in the
        DAG. Setting references (such as ``op.dag`` and task dependencies) is
        done in ``set_task_dag_references`` instead, which is called after the
        DAG is hydrated.
        """
        if "label" not in encoded_op: