code: public final Cache2kBuilder<K, V> exceptionPropagator(ExceptionPropagator<K> ep) {
      config().setExceptionPropagator(wrapCustomizationInstance(ep));
      return this;
    }
docs: Sets customization for propagating loader exceptions. By default loader exceptions
  are wrapped into a {@link org.cache2k.integration.CacheLoaderException}.