Bug 214137 [Markers] Unbound system filters should be bound to problems view.
In 3.3 we supported systemFilters which are not currently picked up by the problems view. We should pick these up for compatiblity.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/views/markers/MarkerFieldFilterGroup.java
*/
	static Collection getProjectsAsCollection(Object[] elements) {
		HashSet projects = new HashSet();
		for (int idx = 0; idx < elements.length; idx++) {
			if (elements[idx] instanceof IResource) {
				projects.add(((IResource) elements[idx]).getProject());
			} else {
				IProject[] mappingProjects = (((ResourceMapping) elements[idx])
						.getProjects());
				for (int i = 0; i < mappingProjects.length; i++) {
					projects.add(mappingProjects[i]);
				}
			}
		}
		return projects;
	}
	private CachedMarkerBuilder builder;
	private IConfigurationElement element;
	private Map EMPTY_MAP = new HashMap();
	private boolean enabled = true;
	private MarkerFieldFilter[] fieldFilters;
	private int scope;
	private String name;
	private String id;
	/**
	 * The entry for testing filters. Cached to prevent garbage.
	 */
	private MarkerEntry testEntry = new MarkerEntry(null);
	private IWorkingSet workingSet;
	private Collection workingSetPaths;