code: protected final void firePropertyChange(PropertyChangeEvent event) {
          PropertyChangeSupport aChangeSupport = this.changeSupport;
          if (aChangeSupport == null) {
              return;
          }
          aChangeSupport.firePropertyChange(event);
      }
docs: General support for reporting bound property changes. Sends the given PropertyChangeEvent to
  any registered PropertyChangeListener.<p>
  
  Most bean setters will invoke the fireXXX methods that get a property name and the old and
  new value. However some frameworks and setters may prefer to use this general method. Also,
  this method allows to fire IndexedPropertyChangeEvents that have been introduced in Java 5.
  
  @param event describes the property change
  
  @since 1.3