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/internal/views/markers/MarkerContentGenerator.java
* 
	 * @param returnMarkers
	 *            {@link Collection} of {@link IMarker}
	 * @param subMonitor
	 * @param filterGroup
	 * @param focusResources
	 *            the resource currently selected
	 */
	private void computeMarkers(Collection returnMarkers,
			SubProgressMonitor subMonitor, MarkerFieldFilterGroup filterGroup,
			IResource[] focusResources) {
		int filterType = filterGroup.getScope();
		switch (filterType) {
		case MarkerFieldFilterGroup.ON_ANY: {
			findMarkers(returnMarkers, new IResource[] { ResourcesPlugin
					.getWorkspace().getRoot() }, filterGroup,
					IResource.DEPTH_INFINITE, subMonitor);
			break;
		}
		case MarkerFieldFilterGroup.ON_SELECTED_ONLY: {
			findMarkers(returnMarkers, focusResources, filterGroup,
					IResource.DEPTH_ZERO, subMonitor);
			break;
		}
		case MarkerFieldFilterGroup.ON_SELECTED_AND_CHILDREN: {
			findMarkers(returnMarkers, focusResources, filterGroup,
					IResource.DEPTH_INFINITE, subMonitor);
			break;
		}
		case MarkerFieldFilterGroup.ON_ANY_IN_SAME_CONTAINER: {