Object writeReplace() {
    return new SerializedForm<>(this);
  }

  @J2ktIncompatible // java.io.ObjectInputStream
  private void readObject(ObjectInputStream stream) throws InvalidObjectException {
    throw new InvalidObjectException("Use SerializedForm");
  }

  // This class is never actually serialized directly, but we have to make the
  // warning go away (and suppressing would suppress for all nested classes too)

        concurrencyLevel,
        this);
  }

  @J2ktIncompatible // java.io.ObjectInputStream
  private void readObject(ObjectInputStream in) throws InvalidObjectException {
    throw new InvalidObjectException("Use SerializationProxy");
  }

  /**
   * The actual object that gets serialized. Unfortunately, readResolve() doesn't get called when a