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
/**
	 * Get the values defined for the receiver.
	 * 
	 * @return Map of values to apply to a {@link MarkerFieldFilter}
	 */
	private Map getValues() {
		try {
			String className = null;
			if (element != null) {
				className = element.getAttribute(ATTRIBUTE_VALUES);
				if (className != null) {
					FiltersContributionParameters parameters = (FiltersContributionParameters) IDEWorkbenchPlugin
							.createExtension(element, ATTRIBUTE_VALUES);
					return parameters.getParameterValues();
				}
			}
		} catch (CoreException e) {
			Policy.handle(e);
			return null;
		}
		return EMPTY_MAP;
	}
	/**
	 * Get the working set for the receiver.
	 * 
	 * @return IWorkingSet
	 */
	IWorkingSet getWorkingSet() {
		return workingSet;
	}