无法通过代理建立隧道。代理通过 https 返回“HTTP/1.1 407”

我面临着java6/8的奇怪行为。我尝试通过需要基本用户身份验证的代理进行隧道传输。通过标准的java身份验证器执行此操作。如果我尝试访问一个https url作为第一个url，则会引发异常：

java.io.IOException：无法通过代理建立隧道。代理返回“HTTP/1.1 407 需要代理身份验证”

但是，如果我先访问http URL，然后再访问https URL，则https访问工作正常。

给定该代码：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.Authenticator;
import java.net.HttpURLConnection;
import java.net.InetSocketAddress;
import java.net.PasswordAuthentication;
import java.net.Proxy;
import java.net.URL;

public class ProxyPass {
    public ProxyPass( String proxyHost, int proxyPort, final String userid, final String password, String url ) {

    try {
            /* Create a HttpURLConnection Object and set the properties */
            URL u = new URL( url );
            Proxy proxy = new Proxy( Proxy.Type.HTTP, new InetSocketAddress( proxyHost, proxyPort ) );
            HttpURLConnection uc = (HttpURLConnection) u.openConnection( proxy );

            Authenticator.setDefault( new Authenticator() {
                @Override
                protected PasswordAuthentication getPasswordAuthentication() {
                    if (getRequestorType().equals( RequestorType.PROXY )) {
                        return new PasswordAuthentication( userid, password.toCharArray() );
                    }
                    return super.getPasswordAuthentication();
                }
            } );
            uc.connect();
            /* Print the content of the url to the console. */
            showContent( uc );
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void showContent( HttpURLConnection uc ) throws IOException {
        InputStream i = uc.getInputStream();
        char c;
        InputStreamReader isr = new InputStreamReader( i );
        BufferedReader br = new BufferedReader( isr );
        String line;
        while ((line = br.readLine()) != null) {
            System.out.println( line );
        }
    }

    public static void main( String[] args ) {
        String proxyhost = "proxyHost";
        int proxyport = proxyPort;
        final String proxylogin = proxyUser;
        final String proxypass = proxyPass;

        String url = "http://www.google.de";
        String surl = "https://www.google.de";

//            new ProxyPass( proxyhost, proxyport, proxylogin, proxypass, url );  // uncomment this line to see that the https request works!
//            System.out.println( url + " ...ok" );   // uncomment this line to see that the https request works!
        new ProxyPass( proxyhost, proxyport, proxylogin, proxypass, surl );
        System.out.println( surl + " ...ok" );
    }

任何建议，想法？