Bug 221337 [Markers] MarkerItem has too much API
We are exposing too much as API in MarkerItem. We should only provide getAtttributeValue and the methods that support PATH_ATTRIBUTE and NAME_ATTRIBUTE as they are tricky. Everything else needs to be pushed down to an internal class. We should mention the relevant IMarker constants for those removed.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/views/markers/internal/MarkerGroup.java
* 
	 * @param markerType
	 * @param entry
	 */
	public void setAsDefault(String markerType, MarkerGroupingEntry entry) {
		addEntry(markerType, new EntryMapping(entry));
	}
	/**
	 * 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);
		if (entries.size() == 0)
			typesToMappings.remove(type);
	}
}