Collection<E> collection) {
    return unmodifiableSet((Set<E>) collection);
  }

  @Override
  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
    return new WrappedSet(key, (Set<V>) collection);
  }

  // Following Javadoc copied from SetMultimap.

  /**
   * {@inheritDoc}
   *
   * <p>Because a {@code SetMultimap} has unique values for a given key, this method returns a

        : collection.iterator();
  }

  /** Set decorator that stays in sync with the multimap values for a key. */
  @WeakOuter
  final class WrappedSet extends WrappedCollection implements Set<V> {
    WrappedSet(@ParametricNullness K key, Set<V> delegate) {
      super(key, delegate, null);
    }

    @Override
    public boolean removeAll(Collection<?> c) {
      if (c.isEmpty()) {

      } else if (collection instanceof SortedSet) {
        return new WrappedSortedSet(key, (SortedSet<V>) collection, null);
      } else if (collection instanceof Set) {
        return new WrappedSet(key, (Set<V>) collection);
      } else {
        return new WrappedCollection(key, collection, null);
      }
    }

    // can't use Serialization writeMultimap and populateMultimap methods since

      } else if (collection instanceof SortedSet) {
        return new WrappedSortedSet(key, (SortedSet<V>) collection, null);
      } else if (collection instanceof Set) {
        return new WrappedSet(key, (Set<V>) collection);
      } else {
        return new WrappedCollection(key, collection, null);
      }
    }

    // can't use Serialization writeMultimap and populateMultimap methods since