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.MTrimContribution} instances.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 */
	protected TrimContributionItemProvider trimContributionItemProvider;
	/**
	 * This creates an adapter for a {@link org.eclipse.e4.ui.model.application.ui.menu.MTrimContribution}.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 */
	@Override
	public Adapter createTrimContributionAdapter() {
		if (trimContributionItemProvider == null) {
			trimContributionItemProvider = new TrimContributionItemProvider(this);
		}
		return trimContributionItemProvider;
	}
	/**
	 * This keeps track of the one adapter used for all {@link org.eclipse.e4.ui.model.application.ui.menu.MTrimContributions} instances.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 */
	protected TrimContributionsItemProvider trimContributionsItemProvider;
	/**
	 * This creates an adapter for a {@link org.eclipse.e4.ui.model.application.ui.menu.MTrimContributions}.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->