@Override
	public Object getAdapter(Class<?> type) {
		if (type == IPropertySheetPage.class)
			return getPropertySheetPage();
		return null;
	}

    public IPropertySheetPage getPropertySheetPage() {
		if (propertySheetPage == null) {
			TransactionalEditingDomain ed = TransactionalEditingDomain.Registry.INSTANCE
					.getEditingDomain(CDOTransactionalEditingDomainImpl.CDO_TED_ID);
			propertySheetPage = new ExtendedPropertySheetPage((AdapterFactoryEditingDomain) ed);
	    	ComposedAdapterFactory emfGlobalFactory = new ComposedAdapterFactory();
			emfGlobalFactory.addAdapterFactory(new RepositorystructureItemProviderAdapterFactory());
			emfGlobalFactory.addAdapterFactory(new ApplicationItemProviderAdapterFactory());
			emfGlobalFactory.addAdapterFactory(new ServiceItemProviderAdapterFactory());
			TransactionalAdapterFactoryContentProvider tafcp =
					new TransactionalAdapterFactoryContentProvider(ed, emfGlobalFactory);
			propertySheetPage.setPropertySourceProvider(tafcp);
    	}
    	return propertySheetPage;
    }

getSite().setSelectionProvider(viewer);

public class GraphitiEditor extends DiagramEditor implements ISelectionProvider {
	private ListenerList listeners = new ListenerList();
	/*
	 * Extend the editor to make it also an ISelectionProvider for properties.
	 * @see org.eclipse.graphiti.ui.editor.DiagramEditor#init(org.eclipse.ui.IEditorSite, org.eclipse.ui.IEditorInput)
	 */
	@Override
	public void init(IEditorSite site, IEditorInput input) throws PartInitException {
		super.init(site, input);
		getSite().setSelectionProvider(this);
	}
	
	@Override
	public void addSelectionChangedListener(ISelectionChangedListener listener) {
		listeners.add(listener);
	}

	@Override
	public ISelection getSelection() {
		// Pass the EObject corresponding to the first selected PE
		PictogramElement[] peArray = getSelectedPictogramElements();
		if (peArray != null && peArray.length > 0) {
			EObject element = (EObject)Graphiti.getLinkService()
					.getBusinessObjectForLinkedPictogramElement(getSelectedPictogramElements()[0]);
			if (element != null)
				return new StructuredSelection(element);
		}
		return StructuredSelection.EMPTY;
	}

	@Override
	public void removeSelectionChangedListener(ISelectionChangedListener listener) {
		listeners.remove(listener);
	}

	@Override
	public void setSelection(ISelection selection) {
		Object[] list = listeners.getListeners();  
		for (int i = 0; i < list.length; i++)
			((ISelectionChangedListener)list[i]).selectionChanged(new SelectionChangedEvent(this, selection));  
	}

java.lang.ClassCastException: org.eclipse.emf.edit.provider.ItemPropertyDescriptor$PropertyValueWrapper cannot be cast to java.lang.String