Java 11+ HttpClient through an authenticated proxy — fixes the 407 Basic-auth tunneling gotcha — https://quantumproxies.io/residential-proxies

JavaProxyExample.java

// Java 11+ HttpClient through an authenticated residential proxy.
//
// THE GOTCHA: since JDK 8u111, Basic auth on HTTPS tunnels is disabled by
// default. Without the system property below you get "407 Proxy
// Authentication Required" forever, even with a correct Authenticator.
//
//   java -Djdk.http.auth.tunneling.disabledSchemes= JavaProxyExample.java
//
// Proxy: QuantumProxies residential — https://quantumproxies.io/residential-proxies
// Credentials: https://app.quantumproxies.io/register

import java.net.*;
import java.net.http.*;

public class JavaProxyExample {
    public static void main(String[] args) throws Exception {
        String user = System.getenv().getOrDefault("QP_USER", "YOUR_USERNAME") + "-country-us";
        String pass = System.getenv().getOrDefault("QP_PASS", "YOUR_PASSWORD");

        HttpClient client = HttpClient.newBuilder()
            .proxy(ProxySelector.of(new InetSocketAddress(
                "residentialboson.quantumproxies.io", 9000)))
            .authenticator(new Authenticator() {
                @Override protected PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication(user, pass.toCharArray());
                }
            })
            .build();

        HttpResponse<String> res = client.send(
            HttpRequest.newBuilder(URI.create("https://ipinfo.io/json")).build(),
            HttpResponse.BodyHandlers.ofString());

        System.out.println(res.body());
    }
}