return standardToArray(array);
        }
      };
    }

    private static <K, V extends @Nullable Object> Iterator<Entry<K, V>> transformEntries(
        Iterator<Entry<K, V>> entries) {
      return Iterators.transform(entries, UnmodifiableEntry::new);
    }

    private UnmodifiableEntry(java.util.Map.Entry<K, V> delegate) {
      this.delegate = checkNotNull(delegate);

 * ordinarily difficult to write iterators for. But using this class, one must implement only the
 * {@link #computeNext} method, and invoke the {@link #endOfData} method when appropriate.
 *
 * <p>Another example is an iterator that skips over null elements in a backing iterator. This could
 * be implemented as:
 *
 * <pre>{@code
 * public static Iterator<String> skipNulls(final Iterator<String> in) {

    }

    @Override
    public void clear() {
        delegate.clear();
        listener.onClear();
    }

    @Override
    public Iterator<E> iterator() {
        reportAggregatingAccess();
        return Iterators.transform(delegate().iterator(), factory::apply);
    }

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

    final Iterator<Entry<K, Collection<V>>> keyIterator;
    @CheckForNull K key;
    @CheckForNull Collection<V> collection;
    Iterator<V> valueIterator;

    Itr() {
      keyIterator = map.entrySet().iterator();
      key = null;
      collection = null;
      valueIterator = Iterators.emptyModifiableIterator();
    }

 * PeekingIterator}</a>.
 *
 * @author Mick Killianey
 * @since 2.0
 */
@DoNotMock("Use Iterators.peekingIterator")
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface PeekingIterator<E extends @Nullable Object> extends Iterator<E> {
  /**
   * Returns the next element in the iteration, without advancing the iteration.
   *

  final transient Collection<E> delegate;

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

  @Override
  public UnmodifiableIterator<E> iterator() {
    return Iterators.unmodifiableIterator(delegate.iterator());
  }

  @Override
  public boolean contains(@Nullable Object object) {
    return object != null && delegate.contains(object);
  }

  @Override

 * PeekingIterator}</a>.
 *
 * @author Mick Killianey
 * @since 2.0
 */
@DoNotMock("Use Iterators.peekingIterator")
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface PeekingIterator<E extends @Nullable Object> extends Iterator<E> {
  /**
   * Returns the next element in the iteration, without advancing the iteration.
   *

   * contains(). Verify that these sets are consistent with the elements of their iterator.
   */
  @CanIgnoreReturnValue
  static <T> Set<T> sanityCheckSet(Set<T> set) {
    assertThat(set).hasSize(Iterators.size(set.iterator()));
    for (Object element : set) {
      assertThat(set).contains(element);
    }
    assertThat(set).doesNotContain(new Object());

 * target iterators on demand. It also requires three additional constructor parameters: {@code
 * elementsToInsert}, the elements to be passed to {@code set()} and {@code add()} calls; {@code
 * features}, the features supported by the iterator; and {@code expectedElements}, the elements the
 * iterator should return in order.
 *

    }

    private boolean removeByProvider(ProviderInternal<?> provider) {
        Iterator<Element<T>> iterator = inserted.iterator();
        while (iterator.hasNext()) {
            Element<T> next = iterator.next();
            if (!next.isRealized() && next.isProvidedBy(provider)) {
                modCount++;
                iterator.remove();
                return true;
            }
        }
        return false;