return Collections.unmodifiableCollection(collection);
  }

  @Override
  public void clear() {
    // Clear each collection, to make previously returned collections empty.
    for (Collection<V> collection : map.values()) {
      collection.clear();
    }
    map.clear();
    totalSize = 0;
  }

  // Views

  /**
   * {@inheritDoc}
   *

      return unmodifiableNavigableSet((NavigableSet<E>) collection);
    } else {
      return unmodifiableSortedSet((SortedSet<E>) collection);
    }
  }

  @Override
  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
    if (collection instanceof NavigableSet) {
      return new WrappedNavigableSet(key, (NavigableSet<V>) collection, null);
    } else {

    new ForwardingWrapperTester()
        .testForwarding(
            Collection.class,
            new Function<Collection, Collection>() {
              @Override
              public Collection apply(Collection delegate) {
                return wrap(delegate);
              }
            });
  }

  private static <T> Collection<T> wrap(Collection<T> delegate) {
    return new ForwardingCollection<T>() {
      @Override

   */
  Collection<V> values();

  /**
   * Returns a view collection of all key-value pairs contained in this multimap, as {@link Entry}
   * instances.
   *
   * <p>Changes to the returned collection or the entries it contains will update the underlying
   * multimap, and vice versa. However, <i>adding</i> to the returned collection is not possible.
   */

    return unmodifiableList((List<E>) collection);
  }

  @Override
  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
    return wrapList(key, (List<V>) collection, null);
  }

  // Following Javadoc copied from ListMultimap.

  /**
   * {@inheritDoc}
   *
   * <p>Because the values for a given key may have duplicates and follow the insertion ordering,

  }

  @Override
  public boolean containsAll(Collection<?> collection) {
    return delegate().containsAll(collection);
  }

  @CanIgnoreReturnValue
  @Override
  public boolean addAll(Collection<? extends E> collection) {
    return delegate().addAll(collection);
  }

  @CanIgnoreReturnValue
  @Override
  public boolean retainAll(Collection<?> collection) {
    return delegate().retainAll(collection);
  }

  }

  @Override
  public boolean containsAll(Collection<?> collection) {
    return delegate().containsAll(collection);
  }

  @CanIgnoreReturnValue
  @Override
  public boolean addAll(Collection<? extends E> collection) {
    return delegate().addAll(collection);
  }

  @CanIgnoreReturnValue
  @Override
  public boolean retainAll(Collection<?> collection) {
    return delegate().retainAll(collection);
  }

                session,
                getIgnorableArtifacts(ignorableArtifacts));
    }

    private Set<Artifact> resolveImpl(
            Collection<? extends MavenProject> projects,
            Collection<String> scopesToCollect,
            Collection<String> scopesToResolve,
            MavenSession session,
            Set<String> projectIds)
            throws ArtifactResolutionException, ArtifactNotFoundException {

      return standardRemove(object);
    }

    @Override
    public boolean removeAll(Collection<?> collection) {
      return standardRemoveAll(collection);
    }

    @Override
    public boolean retainAll(Collection<?> collection) {
      return standardRetainAll(collection);
    }

    @Override
    public Object[] toArray() {
      return standardToArray();
    }

    extends AbstractContainerTester<Collection<E>, E> {

  // TODO: replace this with an accessor.
  protected Collection<E> collection;

  @Override
  protected Collection<E> actualContents() {
    return collection;
  }

  // TODO: dispose of this once collection is encapsulated.
  @Override
  @CanIgnoreReturnValue
  protected Collection<E> resetContainer(Collection<E> newContents) {