code: def from_api_repr(cls, resource):
          
          config = cls(resource["sourceFormat"])
          for optcls in _OPTION_CLASSES:
              opts = resource.get(optcls._RESOURCE_NAME)
              if opts is not None:
                  config._options = optcls.from_api_repr(opts)
                  break
          config._properties = copy.deepcopy(resource)
          return config
docs: Factory: construct an :class:`~.external_config.ExternalConfig`
          instance given its API representation.
  
          Args:
              resource (Dict[str, Any]):
                  Definition of an :class:`~.external_config.ExternalConfig`
                  instance in the same representation as is returned from the
                  API.
  
          Returns:
              :class:`~.external_config.ExternalConfig`:
                  Configuration parsed from ``resource``.