"traceparent": "123",
                        "x_tag": [],
                        "accept": "*/*",
                        "accept-encoding": "gzip, deflate",
                        "connection": "keep-alive",
                        "user-agent": "testclient",
                        "save-data": "true",
                        "if-modified-since": "yesterday",
                        "x-tag": ["one", "two"],

                        "x_tag": [],
                        "host": "testserver",
                        "accept": "*/*",
                        "accept-encoding": "gzip, deflate",
                        "connection": "keep-alive",
                        "user-agent": "testclient",
                    },
                }
            ]
        }
    )


def test_header_param_model_extra(client: TestClient):

### Internal

* 🔨 Enable linenums in MkDocs Material during local live development to simplify highlighting code. PR [#9769](https://github.com/tiangolo/fastapi/pull/9769) by [@tiangolo](https://github.com/tiangolo).