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/advanced/provider/PerspectiveStackItemProvider.java
/**
 * Copyright (c) 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *      IBM Corporation - initial API and implementation
 */
package org.eclipse.e4.ui.model.application.ui.advanced.provider;
import java.util.Collection;
import java.util.List;
import org.eclipse.e4.ui.model.application.MApplicationFactory;
import org.eclipse.e4.ui.model.application.provider.UIElementsEditPlugin;
import org.eclipse.e4.ui.model.application.ui.advanced.MAdvancedFactory;
import org.eclipse.e4.ui.model.application.ui.advanced.MPerspectiveStack;
import org.eclipse.e4.ui.model.application.ui.advanced.impl.AdvancedPackageImpl;
import org.eclipse.e4.ui.model.application.ui.basic.MBasicFactory;
import org.eclipse.e4.ui.model.application.ui.impl.UiPackageImpl;
import org.eclipse.e4.ui.model.application.ui.menu.MMenuFactory;
import org.eclipse.e4.ui.model.application.ui.provider.UIElementItemProvider;
import org.eclipse.emf.common.notify.AdapterFactory;
import org.eclipse.emf.common.notify.Notification;