code: public void setProxy(URI proxy, String userName, String password) {
          setProxy(proxy);
          setClientCredentials(proxy, userName, password);
      }
docs: Set the authenticated proxy server to use.  By default no proxy is configured.
  
  @param proxy    The proxy server, e.g. {@code new URI("http://my.proxy.com:8000")}
  @param userName The username to be used for authentication.
  @param password The password to be used for authentication.