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

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

  @Override
  public boolean containsKey(@Nullable Object key) {
    return delegate().containsKey(key);
  }

  @Override
  public boolean containsValue(@Nullable Object value) {
    return delegate().containsValue(value);

import org.jspecify.annotations.Nullable;

/**
 * Derived suite generators for Guava collection interfaces, split out of the suite builders so that
 * they are available to GWT.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@NullMarked
public final class DerivedGoogleCollectionGenerators {
  public static class MapGenerator<K extends @Nullable Object, V extends @Nullable Object>

      assertTrue(Thread.holdsLock(mutex));
      return delegate.removeLast();
    }

    @Override
    public @Nullable E pollFirst() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.pollFirst();
    }

    @Override
    public @Nullable E pollLast() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.pollLast();
    }

    @Override

  public void testTransformEntrySetContains() {
    Map<@Nullable String, @Nullable Boolean> underlying = new HashMap<>();
    underlying.put("a", null);
    underlying.put("b", true);
    underlying.put(null, true);

    Map<@Nullable String, @Nullable Boolean> map =
        transformValues(
            underlying,
            new Function<@Nullable Boolean, @Nullable Boolean>() {
              @Override

    return size() == 0;
  }

  @Override
  public boolean containsKey(@Nullable Object key) {
    return get(key) != null;
  }

  @Override
  public boolean containsValue(@Nullable Object value) {
    return values().contains(value);
  }

  // Overriding to mark it Nullable
  @Override
  public abstract @Nullable V get(@Nullable Object key);

  /**
   * {@inheritDoc}
   *
   * <p>See <a

   *
   * @since 33.2.0 (available since 22.0 in guava-jre)
   */
  @IgnoreJRERequirement // Users will use this only if they're already using streams.
  public static <T extends @Nullable Object, E extends @Nullable Object, M extends Multiset<E>>
      Collector<T, ?, M> toMultiset(
          Function<? super T, E> elementFunction,
          ToIntFunction<? super T> countFunction,
          Supplier<M> multisetSupplier) {

   *
   * <p>To collect to an {@link ImmutableMultiset}, use {@link
   * ImmutableMultiset#toImmutableMultiset}.
   *
   * @since 22.0
   */
  public static <T extends @Nullable Object, E extends @Nullable Object, M extends Multiset<E>>
      Collector<T, ?, M> toMultiset(
          Function<? super T, E> elementFunction,
          ToIntFunction<? super T> countFunction,
          Supplier<M> multisetSupplier) {

   * href="http://gee.cs.oswego.edu/dl/html/StreamParallelGuidance.html">efficiently splittable</a>.
   * This may harm parallel performance.
   */
  @Beta
  public static <A extends @Nullable Object, B extends @Nullable Object, R extends @Nullable Object>
      Stream<R> zip(
          Stream<A> streamA, Stream<B> streamB, BiFunction<? super A, ? super B, R> function) {
    checkNotNull(streamA);
    checkNotNull(streamB);

    return result;
  }

  @Override
  public @Nullable Entry<E> firstEntry() {
    return delegate().firstEntry();
  }

  @Override
  public @Nullable Entry<E> lastEntry() {
    return delegate().lastEntry();
  }

  @Override
  public @Nullable Entry<E> pollFirstEntry() {
    throw new UnsupportedOperationException();
  }

  @Override
  public @Nullable Entry<E> pollLastEntry() {

            MultimapBuilder.linkedHashKeys().linkedHashSetValues()::<K, V>build),
        ImmutableSetMultimap::copyOf);
  }

  static <
          T extends @Nullable Object,
          K extends @Nullable Object,
          V extends @Nullable Object,
          M extends Multimap<K, V>>
      Collector<T, ?, M> toMultimap(
          Function<? super T, ? extends K> keyFunction,