return null;
        }
      } finally {
        unlock();
        postWriteCleanup();
      }
    }

    // at most one of loadSync/loadAsync may be called for any given LoadingValueReference

    V loadSync(
        K key,
        int hash,
        LoadingValueReference<K, V> loadingValueReference,
        CacheLoader<? super K, V> loader)
        throws ExecutionException {