//////////////////////////////////////////
             IMenuService menuService = (IMenuService)PlatformUI.getWorkbench().getService(IMenuService.class);

           AbstractContributionFactory factory = new AbstractContributionFactory(
                   //"popup:org.eclipse.ui.popup.any?after=additions",null) {
                 "popup:psu.menu2?after=additions",Activator.PLUGIN_ID) {
              
              public void createContributionItems(IServiceLocator serviceLocator, IContributionRoot additions) {

                 CommandContributionItemParameter itemParam = new CommandContributionItemParameter(
                       serviceLocator, "my.id","my.command",SWT.PUSH);
                 itemParam.label = "MyItem";
               
                   CommandContributionItem item = new CommandContributionItem(itemParam);
                   item.setVisible(true);
                   additions.addContributionItem(item,null);

               }

               public void releaseContributionItems(IMenuService menuService,List items) {}

           };
           menuService.addContributionFactory(factory);             
             
             //----------------------------------------------------------------------------

   <extension point="org.eclipse.ui.popupMenus">

      <objectContribution
            id="psu.contextmenu.classeditpart"
            objectClass="org.topcased.modeler.uml.classdiagram.edit.ClassEditPart">
         <menu
               id="psu.menu2"
               label="New Submenu2"
               path="additions">
            <separator
                  name="group2">
            </separator>
         </menu>
         <action
               class="psu.popup.actions.NewAction2"
               enablesFor="1"
               id="psu.newAction2"
               label="New Action2"
               menubarPath="psu.menu2/group2">
         </action>
      </objectContribution>

   </extension>