private static void closeStorage(@Nullable AbstractStateStorage<?, ?> storage)
     throws IOException {
   if (storage != null) {
     synchronized (storage) {
       storage.close();
     }
   }
 }
 private static void wipeStorage(File root, @Nullable AbstractStateStorage<?, ?> storage) {
   if (storage != null) {
     synchronized (storage) {
       storage.wipe();
     }
   } else {
     FileUtil.delete(root);
   }
 }