Bug 249574 [Contributions] ExternalActionManager.addPropertyChangeListener() doesn't register the ListenerList
bundles/org.eclipse.jface/src/org/eclipse/jface/action/ExternalActionManager.java
/**
	 * A simple implementation of the <code>ICallback</code> mechanism that
	 * simply takes a <code>BindingManager</code> and a
	 * <code>CommandManager</code>.
	 * <p>
	 * <b>Note:</b> this class is not intended to be subclassed by clients.
	 * </p>
	 * 
	 * @since 3.1
	 */
	public static class CommandCallback implements
			IBindingManagerListener, IBindingManagerCallback, IExecuteCallback {
		/**
		 * The internationalization bundle for text produced by this class.
		 */
		private static final ResourceBundle RESOURCE_BUNDLE = ResourceBundle
				.getBundle(ExternalActionManager.class.getName());
		/**
		 * The callback capable of responding to whether a command is active.
		 */
		private final IActiveChecker activeChecker;
		
		/**
		 * Check the applicability of firing an execution event for an action.
		 */
		private final IExecuteApplicable applicabilityChecker;
		/**