docs: def _to_dict(self):
          """Return a json dictionary representing this model."""
          _dict = {}
          if hasattr(self, 'credential_id') and self.credential_id is not None:
              _dict['credential_id'] = self.credential_id
          if hasattr(self, 'source_type') and self.source_type is not None:
              _dict['source_type'] = self.source_type
          if hasattr(
                  self,
                  'credential_details') and self.credential_details is not None:
              _dict['credential_details'] = self.credential_details._to_dict()
          return _dict