code: public static HttpProxyTransport connectViaProxy(String host, int port,
  			String proxyHost, int proxyPort, String username, String password,
  			String userAgent) throws IOException, UnknownHostException {
  		return connectViaProxy(host, port, proxyHost, proxyPort, username,
  				password, userAgent, null);
  	}
docs: Connect the socket to a HTTP proxy and request forwarding to our remote
  host.
  
  @param host
  @param port
  @param proxyHost
  @param proxyPort
  @param username
  @param password
  @param userAgent
  @return HttpProxyTransport
  @throws IOException
  @throws UnknownHostException