@Test fun connectExceptionsAreReturnedAsSuppressed() {
    val proxySelector = RecordingProxySelector()
    proxySelector.proxies.add(Proxy(Proxy.Type.HTTP, TestUtil.UNREACHABLE_ADDRESS_IPV4))
    proxySelector.proxies.add(Proxy.NO_PROXY)
    server.close()

    client =
      client
        .newBuilder()
        .proxySelector(proxySelector)

 */

/**
 * Contains classes for managing Maven settings, including global and user-specific
 * configuration stored in settings.xml files. These settings control repository access,
 * authentication, proxies, and other Maven runtime behaviors.
 *
 * @since 4.0.0
 */

  fun doExtensiveHealthChecks(): Boolean

  fun isCanceled(): Boolean

  fun candidateConnection(): RealConnection?

  fun proxySelectStart(url: HttpUrl)

  fun proxySelectEnd(
    url: HttpUrl,
    proxies: List<Proxy>,
  )

  fun dnsStart(socketHost: String)

  fun dnsEnd(
    socketHost: String,
    result: List<InetAddress>,
  )

{* ../../docs_src/header_params/tutorial002_py310.py hl[8] *}

/// warning | Aviso

Antes de definir `convert_underscores` como `False`, lembre-se de que alguns proxies e servidores HTTP não permitem o uso de cabeçalhos com sublinhados.

///

## Cabeçalhos duplicados

É possível receber cabeçalhos duplicados. Isso significa, o mesmo cabeçalho com vários valores.

    call: Call,
    url: HttpUrl,
  ) = logEvent(ProxySelectStart(System.nanoTime(), call, url))

  override fun proxySelectEnd(
    call: Call,
    url: HttpUrl,
    proxies: List<Proxy>,
  ) = logEvent(ProxySelectEnd(System.nanoTime(), call, url, proxies))

  override fun dnsStart(
    call: Call,
    domainName: String,
  ) = logEvent(DnsStart(System.nanoTime(), call, domainName))

  override fun dnsEnd(

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

/// warning

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

///

## Summary { #summary }

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

/// warning | Advertencia

Antes de establecer `convert_underscores` a `False`, ten en cuenta que algunos proxies y servidores HTTP no permiten el uso de headers con guiones bajos.

///

## Headers duplicados

Es posible recibir headers duplicados. Eso significa, el mismo header con múltiples valores.

 * connection the client has many options:
 *
 *  * **HTTP proxy:** a proxy server may be explicitly configured for the client. Otherwise, the
 *    [proxy selector][java.net.ProxySelector] is used. It may return multiple proxies to attempt.
 *  * **IP address:** whether connecting directly to an origin server or a proxy, opening a socket
 *    requires an IP address. The DNS server may return multiple IP addresses to attempt.
 *

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.

{* ../../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.