@Nullable Segment<K, V, E, S> currentSegment;
    @Nullable AtomicReferenceArray<E> currentTable;
    @Nullable E nextEntry;
    @Nullable WriteThroughEntry nextExternal;
    @Nullable WriteThroughEntry lastReturned;

    HashIterator() {
      nextSegmentIndex = segments.length - 1;
      nextTableIndex = -1;
      advance();
    }

    @Override
    public abstract T next();

 *
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible
abstract class AbstractListMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMapBasedMultimap<K, V> implements ListMultimap<K, V> {
  /**
   * Creates a new multimap that uses the provided map.
   *
   * @param map place to store the mapping from each key to its corresponding values
   */

  @Deprecated
  protected ExecutionError(@Nullable String message) {
    super(message);
  }

  /**
   * Creates a new instance with the given detail message and cause. Prefer to provide a
   * non-nullable {@code cause}, as many users expect to find one.
   */
  public ExecutionError(@Nullable String message, @Nullable Error cause) {
    super(message, cause);
  }

  /**

    return delegate().hasEdgeConnecting(endpoints);
  }

  @Override
  public @Nullable V edgeValueOrDefault(N nodeU, N nodeV, @Nullable V defaultValue) {
    return delegate().edgeValueOrDefault(nodeU, nodeV, defaultValue);
  }

  @Override
  public @Nullable V edgeValueOrDefault(EndpointPair<N> endpoints, @Nullable V defaultValue) {
    return delegate().edgeValueOrDefault(endpoints, defaultValue);
  }

  @CanIgnoreReturnValue
  @Override
  public @Nullable V putIfAbsent(K key, V value) {
    return delegate().putIfAbsent(key, value);
  }

  @CanIgnoreReturnValue
  @Override
  public boolean remove(@Nullable Object key, @Nullable Object value) {
    return delegate().remove(key, value);
  }

  @CanIgnoreReturnValue
  @Override
  public @Nullable V replace(K key, V value) {

 *       String}.
 * </ul>
 *
 * This is the same behavior as type-variable usages have to Kotlin and to the Checker Framework.
 * Contrast the method above to:
 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},
 *       typically because the type forbids nullable type arguments: For example, {@code

 *       String}.
 * </ul>
 *
 * This is the same behavior as type-variable usages have to Kotlin and to the Checker Framework.
 * Contrast the method above to:
 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},
 *       typically because the type forbids nullable type arguments: For example, {@code

  // See the note about volatile in the superclass.
  private transient volatile @Nullable CacheEntry<K, V> cacheEntry1;
  private transient volatile @Nullable CacheEntry<K, V> cacheEntry2;

  MapRetrievalCache(Map<K, V> backingMap) {
    super(backingMap);
  }

  @SuppressWarnings("unchecked") // Safe because we only cast if key is found in map.
  @Override
  @Nullable V get(Object key) {
    checkNotNull(key);
    V value = getIfCached(key);

  // the same values as `elements` in hashed positions (plus nulls)
  @VisibleForTesting final transient @Nullable Object[] table;
  // 'and' with an int to get a valid table index.
  private final transient int mask;

  RegularImmutableSet(Object[] elements, int hashCode, @Nullable Object[] table, int mask) {
    this.elements = elements;
    this.hashCode = hashCode;
    this.table = table;
    this.mask = mask;

    READY,
    NOT_READY,
    DONE,
    FAILED,
  }

  private @Nullable T next;

  protected abstract @Nullable T computeNext();

  @CanIgnoreReturnValue
  protected final @Nullable T endOfData() {
    state = State.DONE;
    return null;
  }

  @Override
  public final boolean hasNext() {
    checkState(state != State.FAILED);
    switch (state) {
      case DONE:
        return false;