docs: private void registerExtensions() {
      Iterator<Cache2kExtensionProvider> it =
        ServiceLoader.load(Cache2kExtensionProvider.class, CacheManager.class.getClassLoader()).iterator();
      while (it.hasNext()) {
        try {
          it.next().registerCache2kExtension();
        } catch (ServiceConfigurationError ex) {
          Log.getLog(CacheManager.class.getName()).debug("Error loading cache2k extension", ex);
        }
      }
    }