ObjectDB 2.3.6_16:
The following works in EclipseLink+MySQL and EclipseLink+Oracle:
 public Link(String name, String $url) //throws MalformedURLException
     {
         this.name = name;
         try {
             url = new URL($url);
         } catch (MalformedURLException ex) {
             log_error(ex);
         }
     }  
private URL url;
     public URL getUrl() {
         return url;
     }  
     public void setUrl(URL url) {
         this.url = url;
     }  
I can rewrite this to simply check whether it is a valid URL $url string and storing it.
I can return getURL also as transient to keep my public contract.
But it would be nice to have URLs stored directly.
