implements Serializable {

  transient ObjectCountHashMap<E> backingMap;
  transient long size;

  AbstractMapBasedMultiset(int distinctElements) {
    backingMap = newBackingMap(distinctElements);
  }

  abstract ObjectCountHashMap<E> newBackingMap(int distinctElements);

  @Override
  public final int count(@Nullable Object element) {
    return backingMap.get(element);
  }