Bug 317405 [Model] HandledItem should be abstract
Looks like an oversight the only real types are HandledMenuItem and HandledToolItem.
bundles/org.eclipse.e4.ui.model.workbench.edit/src/org/eclipse/e4/ui/model/application/ui/menu/provider/MenuItemProviderAdapterFactory.java
* This keeps track of the one adapter used for all {@link org.eclipse.e4.ui.model.application.ui.menu.MMenu} instances.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 */
	protected MenuItemProvider menuItemProvider;
	/**
	 * This creates an adapter for a {@link org.eclipse.e4.ui.model.application.ui.menu.MMenu}.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 */
	@Override
	public Adapter createMenuAdapter() {
		if (menuItemProvider == null) {
			menuItemProvider = new MenuItemProvider(this);
		}
		return menuItemProvider;
	}
	/**
	 * This keeps track of the one adapter used for all {@link org.eclipse.e4.ui.model.application.ui.menu.MMenuContribution} instances.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 */
	protected MenuContributionItemProvider menuContributionItemProvider;
	/**
	 * This creates an adapter for a {@link org.eclipse.e4.ui.model.application.ui.menu.MMenuContribution}.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->