assert response.json() == "foo"
    assert response.headers["content-type"] == "application/x-level-1"
    assert "x-level0" in response.headers
    assert "x-level1" in response.headers
    assert "x-level2" not in response.headers
    assert "x-level3" not in response.headers
    assert "x-level4" not in response.headers
    assert "x-level5" not in response.headers


def test_level1_default():

* Auto-generate a "server" in OpenAPI `servers` when there's a `root_path` instead of prefixing all the `paths`:
    * Add a new parameter for `FastAPI` classes: `root_path_in_servers` to disable the auto-generation of `servers`.
    * New docs about `root_path` and `servers` in [Additional Servers](https://fastapi.tiangolo.com/advanced/behind-a-proxy/#additional-servers).