protected void raiseModifying(ScalarEvent e) throws Throwable {
   ScalarListener scalarListener = this.scalarListener;
   if (scalarListener != null) {
     e.getAttributeContext(AttributeScope.LOCAL).addAttribute(AK_SCALAR_LISTENER, scalarListener);
     scalarListener.modifying(e);
   }
 }
 protected void raiseModified(ScalarEvent e) throws Throwable {
   ScalarListener scalarListener =
       (ScalarListener)
           e.getAttributeContext(AttributeScope.LOCAL).removeAttribute(AK_SCALAR_LISTENER);
   if (scalarListener != null) {
     scalarListener.modified(e);
   }
 }