title: Append relative URL to java.net.URL
body: <p>Provided I have a java.net.URL object, pointing to let's say</p>
  
  <p><code>http://example.com/myItems</code> or <code>http://example.com/myItems/</code></p>
  
  <p>Is there some helper somewhere to append some relative URL to this?
  For instance append <code>./myItemId</code> or <code>myItemId</code> to get :
  <code>http://example.com/myItems/myItemId</code></p>