code: def external_data_configuration(self):
          
          prop = self._properties.get("externalDataConfiguration")
          if prop is not None:
              prop = ExternalConfig.from_api_repr(prop)
          return prop
docs: Union[google.cloud.bigquery.ExternalConfig, None]: Configuration for
          an external data source (defaults to :data:`None`).
  
          Raises:
              ValueError: For invalid value types.