code: public void removePropertyChangeListener(String propertyName, PropertyChangeListener listener) {
  		if (children == null) {
  			return;
  		}
  		PropertyChangeSupport child = (PropertyChangeSupport) children.get(propertyName);
  		if (child == null) {
  			return;
  		}
  		child.removePropertyChangeListener(listener);
  	}
docs: Remove a PropertyChangeListener for a specific property.
  
  @param propertyName The name of the property that was listened on.
  @param listener The PropertyChangeListener to be removed