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/MarkerContentGenerator.java
/**
	 * Get the category name from the receiver.
	 */
	String getCategoryName() {
		return configurationElement
				.getAttribute(ATTRIBUTE_DEFAULT_MARKER_GROUPING);
	}
	/**
	 * Return the configuration elements for the receiver.
	 * 
	 * @return IConfigurationElement[]
	 */
	IConfigurationElement[] getFilterReferences() {
		IConfigurationElement[] filterGroups = configurationElement
				.getChildren(ELEMENT_MARKER_FIELD_CONFIGURATION);
		if (generatorExtensions.isEmpty())
			return filterGroups;
		Iterator extensions = generatorExtensions.iterator();
		Collection extendedElements = new ArrayList();
		while (extensions.hasNext()) {
			IConfigurationElement extension = (IConfigurationElement) extensions
					.next();
			IConfigurationElement[] extensionFilters = extension
					.getChildren(ELEMENT_MARKER_FIELD_CONFIGURATION);
			for (int i = 0; i < extensionFilters.length; i++) {
				extendedElements.add(extensionFilters[i]);
			}
		}
		if (extendedElements.size() > 0) {
			IConfigurationElement[] allGroups = new IConfigurationElement[filterGroups.length