Bug 221521 [Markers] New markers API needs to be pared down
We have too much API in some of the new classes and they can be moved to internals
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/views/markers/internal/MarkerGroup.java
GroupMarkerField() {
		}
		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.ui.internal.provisional.views.markers.api.MarkerField#getValue(org.eclipse.ui.internal.provisional.views.markers.api.MarkerItem)
		 */
		public String getValue(MarkerItem item) {
			return MarkerSupportInternalUtilities.getGroupValue(MarkerGroup.this, item);
		}
		/*
		 * (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;
			}