@Override
    public Collection<V> values() {
      Collection<V> result = values;
      return (result == null) ? values = createValues() : result;
    }

    Collection<V> createValues() {
      return new Values<>(this);
    }
  }

  abstract static class IteratorBasedAbstractMap<
          K extends @Nullable Object, V extends @Nullable Object>

    @Override
    public Collection<V> values() {
      Collection<V> result = values;
      return (result == null) ? values = createValues() : result;
    }

    Collection<V> createValues() {
      return new Values<>(this);
    }
  }

  abstract static class IteratorBasedAbstractMap<
          K extends @Nullable Object, V extends @Nullable Object>

    @Override
    public void clear() {
      map.clear();
    }

    @Override
    Set<K> createKeySet() {
      return map.keySet();
    }

    @Override
    Collection<V> createValues() {
      return map.values();
    }

    @Override
    public Set<Entry<K, V>> entries() {
      return map.entrySet();
    }

    @Override

   * corresponding keys.
   */
  @Override
  public ImmutableCollection<V> values() {
    return valueList;
  }

  @Override
  ImmutableCollection<V> createValues() {
    throw new AssertionError("should never be called");
  }

  /**
   * Returns the comparator that orders the keys, which is {@link Ordering#natural()} when the

   * corresponding keys.
   */
  @Override
  public ImmutableCollection<V> values() {
    return valueList;
  }

  @Override
  ImmutableCollection<V> createValues() {
    throw new AssertionError("should never be called");
  }

  /**
   * Returns the comparator that orders the keys, which is {@link Ordering#natural()} when the