String name = helper.getQName(f);
  protected void saveIDRefSingle(EObject o, EStructuralFeature f)  {    EObject value = (EObject)helper.getValue(o, f);    if (value != null)    {      String name = helper.getQName(f);      String id = helper.getIDREF(value);      doc.addAttribute(name, id);    }  }