code: public synchronized void setDelegateMap(PropertyMap delegateMap)
      {
          if (!isCompatibleClass(delegateMap.getMapClass()))
              throw new IllegalArgumentException("The delegate map type (" + delegateMap.getMapClass() + " is an incompatible type with " + _mapClass);
  
          _delegateMap = delegateMap;
      }
docs: Sets a delegate base property map from which values will be derived if not found within
  the local property map.