Multiset<N> successors = getReference(successorsReference);
    if (successors != null) {
      checkState(successors.add(node));
    }
  }

  private static <T> @Nullable T getReference(@Nullable Reference<T> reference) {
    return (reference == null) ? null : reference.get();
  }

    return delegate().offerLast(e);
  }

  @Override
  public @Nullable E peekFirst() {
    return delegate().peekFirst();
  }

  @Override
  public @Nullable E peekLast() {
    return delegate().peekLast();
  }

  @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
  @Override
  public @Nullable E pollFirst() {
    return delegate().pollFirst();
  }

      final C first = first();

      @Override
      protected @Nullable C computeNext(C previous) {
        return equalsOrThrow(previous, first) ? null : domain.previous(previous);
      }
    };
  }

  private static boolean equalsOrThrow(Comparable<?> left, @Nullable Comparable<?> right) {
    return right != null && Range.compareOrThrow(left, right) == 0;
  }

  @Override

import java.util.concurrent.Future;
import org.jspecify.annotations.Nullable;

/**
 * Transforms a value, possibly asynchronously. For an example usage and more information, see
 * {@link Futures#transformAsync(ListenableFuture, AsyncFunction, Executor)}.
 *
 * @author Chris Povirk
 * @since 11.0
 */
@GwtCompatible
public interface AsyncFunction<I extends @Nullable Object, O extends @Nullable Object> {
  /**

package com.google.common.util.concurrent;

import static com.google.common.collect.Sets.newHashSet;

import java.util.Set;
import org.jspecify.annotations.Nullable;

/** Emulation of AggregateFutureState. */
abstract class AggregateFutureState<OutputT extends @Nullable Object>
    extends AbstractFuture.TrustedFuture<OutputT> {
  // Lazily initialized the first time we see an exception; not released until all the input futures

@GwtIncompatible // not worth using in GWT for now
final class CompactLinkedHashMap<K extends @Nullable Object, V extends @Nullable Object>
    extends CompactHashMap<K, V> {
  // TODO(lowasser): implement removeEldestEntry so this can be used as a drop-in replacement

  /** Creates an empty {@code CompactLinkedHashMap} instance. */
  public static <K extends @Nullable Object, V extends @Nullable Object>
      CompactLinkedHashMap<K, V> create() {

  private static final @Nullable Object jla = getJla();

  /**
   * The "getStackTraceElementMethod" method, only available on some JDKs so we use reflection to
   * find it when available. When this is null, use the slow way.
   */
  @J2ktIncompatible @GwtIncompatible // java.lang.reflect
  private static final @Nullable Method getStackTraceElementMethod =

   */
  public static <E extends @Nullable Object> List<E> asList(
      @ParametricNullness E first, @ParametricNullness E second, E[] rest) {
    return new TwoPlusArrayList<>(first, second, rest);
  }

  /**
   * @see Lists#asList(Object, Object[])
   */
  private static final class OnePlusArrayList<E extends @Nullable Object> extends AbstractList<E>
      implements Serializable, RandomAccess {

    this.singleKey = singleKey;
    this.singleValue = singleValue;
    this.inverse = inverse;
  }

  @Override
  public @Nullable V get(@Nullable Object key) {
    return singleKey.equals(key) ? singleValue : null;
  }

  @Override
  public int size() {
    return 1;
  }

  @Override

    @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();