## What we expect from contributors

 * 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.
 *

     */
    public synchronized Proxy getActiveProxy() {
        if (activeProxy == null) {
            java.util.List<Proxy> proxies = getProxies();
            if (proxies != null && !proxies.isEmpty()) {
                for (Proxy proxy : proxies) {
                    if (proxy.isActive()) {
                        activeProxy = proxy;
                        break;
                    }

{* ../../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.

			// 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 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.

    }

    @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");
    }

     */
    @Deprecated
    MavenExecutionRequest addActiveProfiles(List<String> profiles);

    /**
     * @deprecated Since Maven 4: use {@link #getProfileActivation()}.
     */
    @Deprecated
    MavenExecutionRequest setActiveProfiles(List<String> profiles);

    /**
     * @return The list of profiles that the user wants to activate.
     * @deprecated Since Maven 4: use {@link #getProfileActivation()}.

    }

    @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 injectMirror(List<ArtifactRepository> repositories, List<Mirror> mirrors) {}

    @Override
    public void injectProxy(List<ArtifactRepository> repositories, List<Proxy> proxies) {}

    @Override
    public void publish(
            ArtifactRepository repository, File source, String remotePath, ArtifactTransferListener transferListener)
            throws ArtifactTransferFailedException {