Extra links supported for operators coming from third-party packages:

airflow.serialization.serialized_objects.BUILTIN_OPERATOR_EXTRA_LINKS

airflow/serialization/serialized_objects.py
"""Stringifies DAGs and operators contained by var and returns a dict of var."""
        json_dict = {"__version": cls.SERIALIZER_VERSION, "dag": cls.serialize_dag(var)}
        
        cls.validate_schema(json_dict)
        return json_dict
    @classmethod
    def from_dict(cls, serialized_obj: dict) -> 'SerializedDAG':
        """Deserializes a python dict in to the DAG and operators it contains."""
        ver = serialized_obj.get('__version', '<not present>')
        if ver != cls.SERIALIZER_VERSION:
            raise ValueError(f"Unsure how to deserialize version {ver!r}")
        return cls.deserialize_dag(serialized_obj['dag'])
class SerializedTaskGroup(TaskGroup, BaseSerialization):