EDIT

public class OpenReferencingObjectsViewHandler {

    @Execute

    public void execute(EPartService partService) {

    public boolean canExecute(EPartService partService,

            @Named(IServiceConstants.ACTIVE_PART)MPart activePart,

            MHandledMenuItem menuItem) {

        boolean canExecute = false;

        MPart part = partService.findPart(AppModelId.PARTDESCRIPTOR_EU_ETAXONOMY_TAXEDITOR_BULKEDITOR_REFERENCINGOBJECTS_E4_REFERENCINGOBJECTSVIEWE4);

        canExecute = part.equals(activePart)  //we explicitly want to allow calling the view recursively

                || part.getObject() == null ;  //we show the menu item only if the view is not yet open (otherwise by setting the focus data will be shown anyway

                                               //but this may change in future for some data where explicitly calling the view is required

        selectedObjectList = null;

        if (canExecute){

            String commandId = menuItem.getCommand().getElementId();