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/MarkerSupportRegistry.java
* The key for marker type references.
	 */
	public static final String MARKER_TYPE_REFERENCE = "markerTypeReference"; 
	/**
	 * The key for marker support references.
	 */
	public static final String MARKER_SUPPORT_REFERENCE = "markerSupportReference"; 
	private static final String MARKER_CATEGORY = "markerTypeCategory";
	private static final String ATTRIBUTE_MAPPING = "markerAttributeMapping"; 
	/**
	 * The tag for marker grouping.
	 */
	public static final String MARKER_GROUPING = "markerGrouping"; 
	private static final String ATTRIBUTE = "attribute"; 
	private static final String VALUE = "value"; 
	/**
	 * The label attribute
	 */
	static final String LABEL = "label"; 
	private static final String MARKER_ATTRIBUTE_GROUPING = "markerAttributeGrouping";
	private static final String DEFAULT_GROUPING_ENTRY = "defaultGroupingEntry";
	private static final String MARKER_TYPE = "markerType";
	private static final String PRIORITY = "priority"; 
	private static final String MARKER_GROUPING_ENTRY = "markerGroupingEntry"; 
	private static final Object SEVERITY_ID = "org.eclipse.ui.ide.severity";
	/**
	 * The tag for content generators.
	 */
	static final String MARKER_CONTENT_GENERATOR = "markerContentGenerator"; 
	private static final String MARKER_FIELD = "markerField";