code: protected final void firePropertyDataChanged(Collection<? extends D> oldData, Collection<? extends D> newData) {
  		firePropertyDataChanged(new TreeDataEvent(this, oldData, newData, this.data));
  	}
docs: Fire the event for the changes of the user data associated to a node.
  
  @param oldData is the list of old values
  @param newData is the list of new values