docs: def _to_dict(self):
          """Return a json dictionary representing this model."""
          _dict = {}
          if hasattr(self, 'id') and self.id is not None:
              _dict['id'] = self.id
          if hasattr(self, 'metadata') and self.metadata is not None:
              _dict['metadata'] = self.metadata
          if hasattr(self, 'collection_id') and self.collection_id is not None:
              _dict['collection_id'] = self.collection_id
          if hasattr(self,
                     'result_metadata') and self.result_metadata is not None:
              _dict['result_metadata'] = self.result_metadata._to_dict()
          if hasattr(self, 'title') and self.title is not None:
              _dict['title'] = self.title
          if hasattr(self, '_additionalProperties'):
              for _key in self._additionalProperties:
                  _value = getattr(self, _key, None)
                  if _value is not None:
                      _dict[_key] = _value
          return _dict