protected String prepareUrlForExport() {
   StringBuilder sb =
       new StringBuilder(256)
           .append("exported/")
           .append(prepareNameForURL(diagram.getName()))
           .append(".zip?")
           .append(getURLPartToAvoidCaching());
   DiagramServiceServlet.addParameter(sb, InputParameter.DiagramKey.getName(), diagram.getKey());
   return sb.toString();
 }