Bug 214649 [Markers] Allow markerAttributeGroupings and markerGroups to be specified within contentGenerators
With everything at the top level it is hard to see the relation to a contentGenerator and the groups and attribute groupings. These should be sub elements a la menus.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/views/markers/internal/MarkerGroup.java
if (references[i].getAttribute(MarkerSupportConstants.ATTRIBUTE_ID)
					.equals(id)
					&& references[i].getAttribute(
							MarkerSupportConstants.ATTRIBUTE_TYPE).equals(
							MarkerSupportRegistry.MARKER_CONTENT_GENERATOR))
				return true;
		}
		return false;
	}
	/**
	 * Unmap the attributeMarkerGrouping from the receiver.
	 * 
	 * @param attributeMarkerGrouping
	 */
	public void unmap(AttributeMarkerGrouping attributeMarkerGrouping) {
		String type = attributeMarkerGrouping.getMarkerType();
		Collection removed = new ArrayList();
		Collection entries = (Collection) typesToMappings.get(type);
		Iterator mappings = entries.iterator();
		while (mappings.hasNext()) {
			Object mapping = mappings.next();
			if (mapping instanceof AttributeMapping
					&& (((AttributeMapping) mapping).grouping == attributeMarkerGrouping)) {
				removed.add(mapping);
			}
		}
		entries.removeAll(removed);	
	}
}