.keyEquivalence(keyEquivalence)
          .concurrencyLevel(concurrencyLevel);
    }

    @SuppressWarnings("unchecked")
    @J2ktIncompatible // java.io.ObjectInputStream
    void readEntries(ObjectInputStream in) throws IOException, ClassNotFoundException {
      while (true) {
        K key = (K) in.readObject();
        if (key == null) {
          break; // terminator
        }