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
private static final String ATTRIBUTE_CLASS = "class"; 
	/**
	 * The bookmarks generator.
	 */
	public static final String BOOKMARKS_GENERATOR = "org.eclipse.ui.ide.bookmarksGenerator"; 
	/**
	 * The tasks generator.
	 */
	public static final String TASKS_GENERATOR = "org.eclipse.ui.ide.tasksGenerator"; 
	/**
	 * The problems generator.
	 */
	public static final String PROBLEMS_GENERATOR = "org.eclipse.ui.ide.problemsGenerator"; 
	/**
	 * The id for the new markers view.
	 */
	public static final String MARKERS_ID = "org.eclipse.ui.ide.MarkersView"; 
	private static MarkerSupportRegistry singleton;
	
	private static Object creationLock = new Object();
	/**
	 * Get the instance of the registry.
	 * 
	 * @return MarkerSupportRegistry
	 */
	public static MarkerSupportRegistry getInstance() {
		if (singleton == null) {
			synchronized (creationLock) {
				if (singleton == null) {