@J2ktIncompatible
  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
    stream.defaultReadObject();
    int distinctElements = Serialization.readCount(stream);
    setBackingMap(Maps.<E, Count>newHashMap());
    Serialization.populateMultiset(this, stream, distinctElements);
  }

  @GwtIncompatible // Not needed in emulated source.
  @J2ktIncompatible