*/
  protected AbstractSetMultimap(Map<K, Collection<V>> map) {
    super(map);
  }

  @Override
  abstract Set<V> createCollection();

  @Override
  Set<V> createUnmodifiableEmptyCollection() {
    return emptySet();
  }

  @Override
  <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
      Collection<E> collection) {
    return unmodifiableSet((Set<E>) collection);

    super(map);
  }

  @Override
  abstract List<V> createCollection();

  @SuppressWarnings("EmptyList") // ImmutableList doesn't support nullable element types
  @Override
  List<V> createUnmodifiableEmptyCollection() {
    return emptyList();
  }

  @Override
  <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
      Collection<E> collection) {

    }
  }

  /**
   * Creates an unmodifiable, empty collection of values.
   *
   * <p>This is used in {@link #removeAll} on an empty key.
   */
  Collection<V> createUnmodifiableEmptyCollection() {
    return unmodifiableCollectionSubclass(createCollection());
  }

  /**
   * Creates the collection of values for a single key.
   *