code: public ProxySettings setServer(URL url)
      {
          if (url == null)
          {
              return this;
          }
  
          try
          {
              return setServer(url.toURI());
          }
          catch (URISyntaxException e)
          {
              throw new IllegalArgumentException(e);
          }
      }
docs: Set the proxy server by a URL. See the description of
  {@link #setServer(URI)} about how the parameters are updated.
  
  @param url
  The URL of the proxy server. If {@code null} is given,
  none of the parameters are updated.
  
  @return
  {@code this} object.
  
  @throws IllegalArgumentException
  Failed to convert the given URL to a {@link URI} instance.