assertNotInstantiable(new TypeToken<ImmutableMultiset<EmptyEnum>>() {});
  }

  public void testImmutableCollection() {
    assertFreshInstance(new TypeToken<ImmutableCollection<String>>() {});
    assertNotInstantiable(new TypeToken<ImmutableCollection<EmptyEnum>>() {});
  }

  public void testImmutableMap() {
    assertFreshInstance(new TypeToken<ImmutableMap<String, Integer>>() {});
  }

    if (elements instanceof ImmutableCollection) {
      /*
       * TODO: When given an ImmutableList that's a sublist, copy the referenced
       * portion of the array into a new array to save space?
       */
      @SuppressWarnings("unchecked") // all supported methods are covariant
      ImmutableCollection<E> list = (ImmutableCollection<E>) elements;
      return list.asList();
    }

        Collection<?> collection = (Collection<?>) elements;
        ensureRoomFor(collection.size());
        if (collection instanceof ImmutableCollection) {
          ImmutableCollection<?> immutableCollection = (ImmutableCollection<?>) collection;
          size = immutableCollection.copyIntoArray(contents, size);
          return this;
        }
      }
      super.addAll(elements);
      return this;
    }

          }
        });
  }

  @Override
  ImmutableSet<K> createKeySet() {
    return ImmutableSet.unsafeDelegate(delegate.keySet());
  }

  @Override
  ImmutableCollection<V> createValues() {
    return ImmutableCollection.unsafeDelegate(delegate.values());
  }

  @Override
  public int size() {
    return delegate.size();
  }

  @Override

 *
 * @author Jesse Wilson
 * @author Kevin Bourrillion
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
final class ImmutableMapValues<K, V> extends ImmutableCollection<V> {
  private final ImmutableMap<K, V> map;

  ImmutableMapValues(ImmutableMap<K, V> map) {
    this.map = map;
  }

  @Override
  public int size() {
    return map.size();
  }

  @Override

      }
    };
  }

  @LazyInit @RetainedWith @CheckForNull private transient ImmutableCollection<V> values;

  /**
   * Returns an immutable collection of the values in this map, in the same order that they appear
   * in {@link #entrySet}.
   */
  @Override
  public ImmutableCollection<V> values() {
    ImmutableCollection<V> result = values;
    return (result == null) ? values = createValues() : result;
  }

  final UnmodifiableIterator<Cell<R, C, V>> cellIterator() {
    throw new AssertionError("should never be called");
  }

  @Override
  public ImmutableCollection<V> values() {
    return (ImmutableCollection<V>) super.values();
  }

  @Override
  abstract ImmutableCollection<V> createValues();

  @Override
  final Iterator<V> valuesIterator() {
    throw new AssertionError("should never be called");
  }

   */
  public static <E> ImmutableList<E> copyOf(Collection<? extends E> elements) {
    if (elements instanceof ImmutableCollection) {
      @SuppressWarnings("unchecked") // all supported methods are covariant
      ImmutableList<E> list = ((ImmutableCollection<E>) elements).asList();
      return list.isPartialView() ? ImmutableList.<E>asImmutableList(list.toArray()) : list;
    }

    entries.forEach(e -> action.accept(e.getKey(), e.getValue()));
  }

  @Override
  ImmutableSet<K> createKeySet() {
    return new ImmutableMapKeySet<>(this);
  }

  @Override
  ImmutableCollection<V> createValues() {
    return new ImmutableMapValues<>(this);
  }

  @Override
  boolean isPartialView() {
    return false;
  }

  // redeclare to help optimizers with b/310253115

 * delegation to save code size.
 *
 * @author Hayward Chan
 */
// TODO: Make this class GWT serializable.
@ElementTypesAreNonnullByDefault
class ForwardingImmutableCollection<E> extends ImmutableCollection<E> {

  final transient Collection<E> delegate;

  ForwardingImmutableCollection(Collection<E> delegate) {
    this.delegate = delegate;
  }

  @Override
  public UnmodifiableIterator<E> iterator() {