@Override
 public FunctionConfigurationBundle getFunctionConfiguration(final Instant version) {
   final List<FunctionConfiguration> configs = new ArrayList<FunctionConfiguration>();
   for (final FunctionConfigurationSource source : getSources()) {
     configs.addAll(source.getFunctionConfiguration(version).getFunctions());
   }
   return new FunctionConfigurationBundle(configs);
 }
 @Override
 public ChangeManager changeManager() {
   PassthroughChangeManager changeManager = null;
   for (FunctionConfigurationSource source : getSources()) {
     final ChangeManager cm = source.changeManager();
     if (cm != DummyChangeManager.INSTANCE) {
       if (changeManager == null) {
         changeManager = new PassthroughChangeManager();
       }
       changeManager.addChangeManager(cm);
     }
   }
   if (changeManager == null) {
     return DummyChangeManager.INSTANCE;
   } else {
     return changeManager;
   }
 }