/**
  * CloneObject.
  *
  * @param clone the ListButtonExtension.
  */
 protected void cloneObject(ListButtonExtension clone) {
   super.cloneObject(clone);
   if ((this.getSelection() != null)) {
     clone.setSelection(this.getSelection().cloneObject());
   }
   if ((this.getModification() != null)) {
     clone.setModification(this.getModification().cloneObject());
   }
 }
 @Override
 public Set<NabuccoProperty> getProperties() {
   Set<NabuccoProperty> properties = super.getProperties();
   properties.add(
       super.createProperty(
           ListButtonExtension.getPropertyDescriptor(SELECTION), this.getSelection(), null));
   properties.add(
       super.createProperty(
           ListButtonExtension.getPropertyDescriptor(MODIFICATION), this.getModification(), null));
   return properties;
 }