/**
  * Underlying layers <i>must</i> load state first.<br>
  * If this is not done, {@link IStructuralChangeEvent} from underlying<br>
  * layers will reset caches after state has been loaded
  */
 @Override
 public void loadState(String prefix, Properties properties) {
   super.loadState(prefix, properties);
   underlyingLayer.loadState(prefix, properties);
 }