It can contain several fields.

                * `name`: (`str`) **REQUIRED** (if a `license_info` is set). The
                    license name used for the API.
                * `identifier`: (`str`) An [SPDX](https://spdx.dev/) license expression
                    for the API. The `identifier` field is mutually exclusive of the `url`
                    field. Available since OpenAPI 3.1.0, FastAPI 0.99.0.

                response_field = create_response_field(name=response_name, type_=model)
                response_fields[additional_status_code] = response_field
        if response_fields:
            self.response_fields: Dict[Union[int, str], ModelField] = response_fields
        else:
            self.response_fields = {}

        assert callable(endpoint), "An endpoint must be a callable"