Collection<String> values = map.values();
    values.remove("4");
    assertFalse(underlying.containsKey("d"));

    Iterator<String> valueIterator = values.iterator();
    valueIterator.next();
    valueIterator.remove();
    assertFalse(underlying.containsKey("e"));

    Set<Entry<String, String>> entries = map.entrySet();
    Entry<String, String> firstEntry = entries.iterator().next();

    Collection<String> values = map.values();
    values.remove("4");
    assertFalse(underlying.containsKey("d"));

    Iterator<String> valueIterator = values.iterator();
    valueIterator.next();
    valueIterator.remove();
    assertFalse(underlying.containsKey("e"));

    Set<Entry<String, String>> entries = map.entrySet();
    Entry<String, String> firstEntry = entries.iterator().next();

    public boolean hasNext() {
      return keyIterator.hasNext() || valueIterator.hasNext();
    }

    @Override
    @ParametricNullness
    public T next() {
      if (!valueIterator.hasNext()) {
        Entry<K, Collection<V>> mapEntry = keyIterator.next();
        key = mapEntry.getKey();
        collection = mapEntry.getValue();
        valueIterator = collection.iterator();
      }
      /*

    Collection<String> values = map.values();
    values.remove("4");
    assertFalse(underlying.containsKey("d"));

    Iterator<String> valueIterator = values.iterator();
    valueIterator.next();
    valueIterator.remove();
    assertFalse(underlying.containsKey("e"));

    Set<Entry<String, String>> entries = map.entrySet();
    Entry<String, String> firstEntry = entries.iterator().next();

    return (ImmutableCollection<V>) super.values();
  }

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

  @Override
  UnmodifiableIterator<V> valueIterator() {
    return new UnmodifiableIterator<V>() {
      final Iterator<? extends ImmutableCollection<V>> valueCollectionItr = map.values().iterator();
      Iterator<V> valueItr = emptyIterator();

      @Override

    return (ImmutableCollection<V>) super.values();
  }

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

  @Override
  UnmodifiableIterator<V> valueIterator() {
    return new UnmodifiableIterator<V>() {
      final Iterator<? extends ImmutableCollection<V>> valueCollectionItr = map.values().iterator();
      Iterator<V> valueItr = emptyIterator();

      @Override

      @ParametricNullness
      K transform(Entry<K, V> entry) {
        return entry.getKey();
      }
    };
  }

  static <K extends @Nullable Object, V extends @Nullable Object> Iterator<V> valueIterator(
      Iterator<Entry<K, V>> entryIterator) {
    return new TransformedIterator<Entry<K, V>, V>(entryIterator) {
      @Override
      @ParametricNullness
      V transform(Entry<K, V> entry) {