Bug 258810 [Markers] Markers for the entire workspace show up when working set empty
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/views/markers/MarkerFieldFilterGroup.java
private static final String ATTRIBUTE_VALUES = "values"; 
	private static final IProject[] EMPTY_PROJECT_ARRAY = new IProject[0];
	/**
	 * Constant for any element.
	 */
	static final int ON_ANY = 0;
	/**
	 * Constant for any element in same container.
	 */
	static final int ON_ANY_IN_SAME_CONTAINER = 3;
	/**
	 * Constant for selected element and children.
	 */
	static final int ON_SELECTED_AND_CHILDREN = 2;
	/**
	 * Constant for any selected element only.
	 */
	static final int ON_SELECTED_ONLY = 1;
	/**
	 * Constant for on working set.
	 */
	static final int ON_WORKING_SET = 4;
	static final String TAG_ENABLED = "enabled"; 
	private static final String TAG_SCOPE = "scope"; 
	private static final String TAG_FIELD_FILTER_ENTRY = "fieldFilter"; 
	private static final String TAG_WORKING_SET = "workingSet"; 
	
	private static String USER = "USER"; 
	/**
	 * Returns the set of projects that contain the given set of resources.