Bug 214648 [Markers] AttributeMarkerGroupings and GroupingEntries not being cleaned up on removal
We are still leaving the references to AttributeMarkerGroupings and GroupingEntries when we unload
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/views/markers/internal/MarkerSupportRegistry.java
registeredFilters.put(filter.getId(), filter);
				tracker.registerObject(extension, filter,
						IExtensionTracker.REF_STRONG);
				continue;
			}
			if (element.getName().equals(MARKER_GROUPING)) {
				String id = element
						.getAttribute(MarkerSupportConstants.ATTRIBUTE_ID);
				MarkerGroup group;
				if (id.equals(Util.TYPE_MARKER_GROUPING_ID))
					group = new TypeMarkerGroup(element.getAttribute(LABEL));
				else
					group = new MarkerGroup(element);
				markerGroups.put(group.getId(), group);
				tracker.registerObject(extension, group,
						IExtensionTracker.REF_STRONG);
				continue;
			}
			if (element.getName().equals(MARKER_GROUPING_ENTRY)) {
				MarkerGroupingEntry entry = new MarkerGroupingEntry(element
						.getAttribute(LABEL), element
						.getAttribute(MarkerSupportConstants.ATTRIBUTE_ID),
						(Integer.valueOf(element.getAttribute(PRIORITY))
								.intValue()));
				String groupName = element.getAttribute(MARKER_GROUPING);
				Collection entries;
				if (groupingEntries.containsKey(groupName)) {
					entries = (Collection) groupingEntries.get(groupName);
				} else {
					entries = new HashSet();