contentService = aSite.getContentService();
extensionStateModel = contentService
.findStateModel(WorkingSetContentProvider.EXTENSION_ID);
workingSetActionGroup = new WorkingSetFilterActionGroup(aSite
.getViewSite().getShell(), filterChangeListener);
if (extensionStateModel != null) {
workingSetRootModeActionGroup = new WorkingSetRootModeActionGroup(
viewer, extensionStateModel);