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/MarkerGroup.java
MarkerGroupingEntry groupingEntry = findGroupValue(item
							.getMarker().getType(), item.getMarker());
					return groupingEntry.getLabel();
				} catch (CoreException exception) {
					return Util.EMPTY_STRING;
				}
			}
			return item.getDescription();
		}
		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.ui.internal.provisional.views.markers.api.MarkerField#compare(org.eclipse.ui.internal.provisional.views.markers.api.MarkerItem,
		 *      org.eclipse.ui.internal.provisional.views.markers.api.MarkerItem)
		 */
		public int compare(MarkerItem item1, MarkerItem item2) {
			
			if (item1.getMarker() == null) {
				if (item2.getMarker() == null)
					return 0;
				return 1;
			}
			
			if (item2.getMarker() == null)
				return -1;
			try {
				return (findGroupValue(item2.getMarker().getType(),
						item2.getMarker()).getPriority() - findGroupValue(
						item1.getMarker().getType(), item1.getMarker())
						.getPriority());