Bug 112490 Patch to fix the mess I made
I have done bad things. I now prostrate myself and humbly ask that some gracious soul submit this patch (which I will attach forthwith) so that I may redeem myself. Basically, I (well really John but I made him do it) moved the ResourceMapping stuff to API but we missed a few things that needed to be done, causing great grief to the JDT team. Please spare the lashes as I have a low pain threshold.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/model/WorkingSetAdapterFactory.java
public Object[] getChildren(Object o) {
            if (o instanceof IWorkingSet) {
                IWorkingSet set = (IWorkingSet) o;
                return set.getElements();
            }
            return null;
        }
        public ImageDescriptor getImageDescriptor(Object o) {
            if (o instanceof IWorkingSet) {
                IWorkingSet set = (IWorkingSet) o;
                return set.getImage();
            }
            return null;
        }
        public String getLabel(Object o) {
            if (o instanceof IWorkingSet) {
                IWorkingSet set = (IWorkingSet) o;
                return set.getName();
            }
            return null;
        }
        public Object getParent(Object o) {
            return null;
        }
        
    }
    private IContributorResourceAdapter2 contributorResourceAdapter = new ContributorResourceAdapter();
    private IWorkbenchAdapter workbenchAdapter = new WorkbenchAdapter();
    
    /* (non-Javadoc)