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
for (IExtension extension : extensions) {
			IContributor contributor = extension.getContributor();
			Collection<IExtension> exts = mappedExtensions.get(contributor.getName());
			if (exts == null) {
				mappedExtensions.put(contributor.getName(), exts = new ArrayList<IExtension>());
			}
			exts.add(extension);
			requires.put(contributor.getName(), new HashSet<String>());
			depends.put(contributor.getName(), new HashSet<String>());
		}
		
		for (String bundleId : mappedExtensions.keySet()) {
			assert requires.containsKey(bundleId) && depends.containsKey(bundleId);
			for (RequiredBundle requiredBundle : admin.getRequiredBundles(bundleId)) {
				assert requiredBundle.getSymbolicName().equals(bundleId);
				for (Bundle dependentBundle : requiredBundle.getRequiringBundles()) {
					if (!mappedExtensions.containsKey(dependentBundle.getSymbolicName())) {
						
						continue;
					}
					String depBundleId = dependentBundle.getSymbolicName();
					Collection<String> depBundleReqs = requires.get(depBundleId);
					depBundleReqs.add(bundleId);
					Collection<String> bundleDeps = depends.get(bundleId);
					assert bundleDeps != null;