code: public ProxySettings setServer(String uri)
      {
          if (uri == null)
          {
              return this;
          }
  
          return setServer(URI.create(uri));
      }
docs: Set the proxy server by a URI. See the description of
  {@link #setServer(URI)} about how the parameters are updated.
  
  @param uri
  The URI 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 string to a {@link URI} instance.