Bug 331010 Track Model-Element contributors
We need to track which bundle contributed an model element to e.g. look up translations in the right package
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/ModelAssembler.java
* done in-place.
	 * 
	 * @param extensions
	 *            the list of extensions to be sorted
	 * @return the same list of extensions in a topologically-sorted order
	 */
	private IExtension[] topoSort(IExtension[] extensions) {
		if (extensions.length == 0) {
			return extensions;
		}
		PackageAdmin admin = Activator.getDefault().getBundleAdmin();
		final Map<String, Collection<IExtension>> mappedExtensions = new HashMap<String, Collection<IExtension>>();
		
		final Map<String, Collection<String>> requires = new HashMap<String, Collection<String>>();
		
		final Map<String, Collection<String>> depends = new HashMap<String, Collection<String>>();