Bug 205049 Other plug-ins should be able to define default content generator
Currently only the content generator can define which plug-ins it can be the default for - we need a way for plug-ins to refer back to the marker support for thier own generator.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/provisional/views/markers/MarkerContentGenerator.java
index++;
		}
		return new MarkerMap(entries);
	}
	/**
	 * Iterate through the return markers. If they do not exist in matching
	 * remove them.
	 * 
	 * @param matching
	 * @param returnMarkers
	 */
	private void findIntersection(Collection matching, Collection returnMarkers) {
		HashSet removeMarkers = new HashSet();
		Iterator existing = returnMarkers.iterator();
		while (existing.hasNext()) {
			Object next = existing.next();
			if (matching.contains(next))
				continue;
			removeMarkers.add(next);
		}
		returnMarkers.removeAll(removeMarkers);
	}
	/**
	 * Get the all of the fields that this content generator is using.
	 * 
	 * @return {@link MarkerField}[]
	 */
	public MarkerField[] getAllFields() {
		return allFields;
	}