final Iterator<Entry<K, V>> entryIterator) {
    return new UnmodifiableIterator<Entry<K, V>>() {
      @Override
      public boolean hasNext() {
        return entryIterator.hasNext();
      }

      @Override
      public Entry<K, V> next() {
        return unmodifiableEntry(entryIterator.next());
      }
    };
  }

          final Iterator<Entry<K, V>> entryIterator) {
    return new UnmodifiableIterator<Entry<K, V>>() {
      @Override
      public boolean hasNext() {
        return entryIterator.hasNext();
      }

      @Override
      public Entry<K, V> next() {
        return unmodifiableEntry(entryIterator.next());
      }
    };
  }

  final class ValueIterator extends HashIterator<V> {

    @Override
    public V next() {
      return nextEntry().getValue();
    }
  }

  /**
   * Custom Entry class used by EntryIterator.next(), that relays setValue changes to the underlying
   * map.
   */
  final class WriteThroughEntry implements Entry<K, V> {
    final K key; // non-null
    V value; // non-null