* }</pre>
   *
   * ... prints {@code {a=2.0, b=3.0}}.
   *
   * <p>Changes in the underlying map are reflected in this view. Conversely, this view supports
   * removal operations, and these are reflected in the underlying map.
   *
   * <p>It's acceptable for the underlying map to contain null keys, and even null values provided

   *     Executor)}.
   * @param closingExecutor the future's result will be closed on this executor
   * @deprecated Creating {@link Future}s of closeable types is dangerous in general because the
   *     underlying value may never be closed if the {@link Future} is canceled after its operation
   *     begins. Consider replacing code that creates {@link ListenableFuture}s of closeable types,

    @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

    WriteThroughEntry(K key, V value) {
      this.key = key;

    @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

    WriteThroughEntry(K key, V value) {
      this.key = key;