{* ../../docs_src/header_param_models/tutorial003_an_py310.py hl[19] *}

/// warning | Atenção

Antes de definir `convert_underscores` como `False`, tenha em mente que alguns proxies e servidores HTTP não permitem o uso de cabeçalhos com sublinhados.

///

## Resumo { #summary }

{* ../../docs_src/header_params/tutorial002_an_py310.py hl[10] *}

/// warning

Before setting `convert_underscores` to `False`, bear in mind that some HTTP proxies and servers disallow the usage of headers with underscores.

///

## Duplicate headers { #duplicate-headers }

It is possible to receive duplicate headers. That means, the same header with multiple values.

Uvicorn will expect the proxy to access Uvicorn at `http://127.0.0.1:8000/app`, and then it would be the proxy's responsibility to add the extra `/api/v1` prefix on top.

## About proxies with a stripped path prefix { #about-proxies-with-a-stripped-path-prefix }

Keep in mind that a proxy with stripped path prefix is only one of the ways to configure it.

			// Only grab the first (client) address. Note that '192.168.0.1,
			// 10.1.1.1' is a valid key for X-Forwarded-For where addresses after
			// the first may represent forwarding proxies earlier in the chain.
			s := strings.Index(fwd, ", ")
			if s == -1 {
				s = len(fwd)
			}
			addr = fwd[:s]
		}
	}

	if addr == "" {
		if fwd := r.Header.Get(xRealIP); fwd != "" {

Uvicorn esperará que el proxy acceda a Uvicorn en `http://127.0.0.1:8000/app`, y luego será responsabilidad del proxy añadir el prefijo extra `/api/v1` encima.

## Sobre proxies con un prefijo de path eliminado { #about-proxies-with-a-stripped-path-prefix }

Ten en cuenta que un proxy con prefijo de path eliminado es solo una de las formas de configurarlo.

    }

    @Override public void proxySelectStart(Call call, HttpUrl url) {
      printEvent("proxySelectStart");
    }

    @Override public void proxySelectEnd(Call call, HttpUrl url, List<Proxy> proxies) {
      printEvent("proxySelectEnd");
    }

    @Override public void callStart(Call call) {
      printEvent("callStart");
    }

    @Override public void dnsStart(Call call, String domainName) {

    }

    @Override public void proxySelectStart(Call call, HttpUrl url) {
      printEvent("proxySelectStart");
    }

    @Override public void proxySelectEnd(Call call, HttpUrl url, List<Proxy> proxies) {
      printEvent("proxySelectEnd");
    }

    @Override public void dnsStart(Call call, String domainName) {
      printEvent("dnsStart");
    }

     * @return requested (de-)activation(s) of profile(s) in this execution. Never {@code null}.
     */
    ProfileActivation getProfileActivation();

    // Proxies
    List<Proxy> getProxies();

    MavenExecutionRequest setProxies(List<Proxy> proxies);

    MavenExecutionRequest addProxy(Proxy proxy);

    // Servers
    List<Server> getServers();

Como no se recomienda, la documentación interactiva con Swagger UI no mostrará la documentación para el body cuando se usa `GET`, y los proxies intermedios podrían no soportarlo.

///

## Importar `BaseModel` de Pydantic { #import-pydantics-basemodel }

Primero, necesitas importar `BaseModel` de `pydantic`:

    val proxySelector = RecordingProxySelector()
    val socketAddress = InetSocketAddress.createUnresolved("myproxy", 8008)
    proxySelector.proxies.add(Proxy(Proxy.Type.HTTP, socketAddress))

    // Define two host names for the DNS routing of fake proxy servers
    val proxyServer1 = InetAddress.getByAddress("proxyServer1", byteArrayOf(127, 0, 0, 2))