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();
  }

   * override {@link #toArray(Object[])}, you may wish to override {@link #toArray} to forward to
   * this implementation.
   *
   * @since 7.0
   */
  protected @Nullable Object[] standardToArray() {
    @Nullable Object[] newArray = new @Nullable Object[size()];
    return toArray(newArray);
  }

  /**
   * A sensible definition of {@link #toArray(Object[])} in terms of {@link #size} and {@link

   * override {@link #toArray(Object[])}, you may wish to override {@link #toArray} to forward to
   * this implementation.
   *
   * @since 7.0
   */
  protected @Nullable Object[] standardToArray() {
    @Nullable Object[] newArray = new @Nullable Object[size()];
    return toArray(newArray);
  }

  /**
   * A sensible definition of {@link #toArray(Object[])} in terms of {@link #size} and {@link

public final class CollectorTester<
    T extends @Nullable Object, A extends @Nullable Object, R extends @Nullable Object> {
  /**
   * Creates a {@code CollectorTester} for the specified {@code Collector}. The result of the {@code
   * Collector} will be compared to the expected value using {@link Object#equals}.
   */
  public static <T extends @Nullable Object, A extends @Nullable Object, R extends @Nullable Object>

import org.jspecify.annotations.Nullable;

/**
 * Skeletal implementation of {@link NavigableMap}.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible
abstract class AbstractNavigableMap<K extends @Nullable Object, V extends @Nullable Object>
    extends IteratorBasedAbstractMap<K, V> implements NavigableMap<K, V> {

  @Override
  public abstract @Nullable V get(@Nullable Object key);

  @Override

  }

  @Override
  public @Nullable E lower(E element) {
    int index = headIndex(element, false) - 1;
    return (index == -1) ? null : elements.get(index);
  }

  @Override
  public @Nullable E floor(E element) {
    int index = headIndex(element, true) - 1;
    return (index == -1) ? null : elements.get(index);
  }

  @Override
  public @Nullable E ceiling(E element) {

  }

  private static final class TestCallable implements AsyncCallable<@Nullable Void> {

    private final ListenableFuture<@Nullable Void> future;
    private boolean called = false;

    private TestCallable(ListenableFuture<@Nullable Void> future) {
      this.future = future;
    }

    @Override
    public ListenableFuture<@Nullable Void> call() throws Exception {
      called = true;
      return future;

   * @throws IllegalArgumentException if {@code size} is nonpositive
   */
  public static <T extends @Nullable Object>
      UnmodifiableIterator<List<@Nullable T>> paddedPartition(Iterator<T> iterator, int size) {
    return partitionImpl(iterator, size, true);
  }

  private static <T extends @Nullable Object> UnmodifiableIterator<List<@Nullable T>> partitionImpl(
      Iterator<T> iterator, int size, boolean pad) {
    checkNotNull(iterator);

   * @throws IllegalArgumentException if {@code size} is nonpositive
   */
  public static <T extends @Nullable Object>
      UnmodifiableIterator<List<@Nullable T>> paddedPartition(Iterator<T> iterator, int size) {
    return partitionImpl(iterator, size, true);
  }

  private static <T extends @Nullable Object> UnmodifiableIterator<List<@Nullable T>> partitionImpl(
      Iterator<T> iterator, int size, boolean pad) {
    checkNotNull(iterator);

    }

    @Override
    @Nullable C correctedDoForward(@Nullable A a) {
      return second.correctedDoForward(first.correctedDoForward(a));
    }

    @Override
    @Nullable A correctedDoBackward(@Nullable C c) {
      return first.correctedDoBackward(second.correctedDoBackward(c));
    }

    @Override
    public boolean equals(@Nullable Object object) {