Bug 11748 switch to new DecoratorManager API
From the workbench change notes: API changes IWorkbenchPartSite.getDecoratorManager() - As the DecoratorManager has proven to be required for more than just IWorkbenchPartSites we have moved getDecoratorManager() to IWorkbench and deprecated the getDecoratorManager() in IWorkbenchPartSite. The one in IWorkbenchPartSite will be removed after the other Eclipse components have had a chance to switch to the new API.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaOutlinePage.java
public void setAction(String actionID, IAction action) {
		Assert.isNotNull(actionID);
		if (action == null)
			fActions.remove(actionID);
		else
			fActions.put(actionID, action);
	}
	
	public IAction getAction(String actionID) {
		Assert.isNotNull(actionID);
		return (IAction) fActions.get(actionID);
	}
	
	/**
	 * Convenience method to add the action installed under the given actionID to the
	 * specified group of the menu.
	 */
	protected void addAction(IMenuManager menu, String group, String actionID) {
		IAction action= getAction(actionID);
		if (action != null) {
			if (action instanceof IUpdate)
				((IUpdate) action).update();
				
			if (action.isEnabled()) {
		 		IMenuManager subMenu= menu.findMenuUsingPath(group);
		 		if (subMenu != null)
		 			subMenu.add(action);
		 		else
		 			menu.appendToGroup(group, action);