*
   * @since 15.0
   */
  public static <E extends @Nullable Object> Funnel<Iterable<? extends E>> sequentialFunnel(
      Funnel<E> elementFunnel) {
    return new SequentialFunnel<>(elementFunnel);
  }

  private static final class SequentialFunnel<E extends @Nullable Object>
      implements Funnel<Iterable<? extends E>> {
    private final Funnel<E> elementFunnel;

  private static final class NewExecutionListQueue {
    static final Logger log = Logger.getLogger(NewExecutionListQueue.class.getName());

    @GuardedBy("this")
    private @Nullable RunnableExecutorPair head;

    @GuardedBy("this")
    private @Nullable RunnableExecutorPair tail;

    @GuardedBy("this")
    private boolean executed;

    void add(Runnable runnable, Executor executor) {

   * created multimaps.
   *
   * @since 2.0
   */
  @DoNotMock
  public static class Builder<K, V> {
    @Nullable Map<K, ImmutableCollection.Builder<V>> builderMap;
    @Nullable Comparator<? super K> keyComparator;
    @Nullable Comparator<? super V> valueComparator;
    int expectedValuesPerKey = ImmutableCollection.Builder.DEFAULT_INITIAL_CAPACITY;

    /**

    checkNotNull(valueComparator);
    return Comparator.<Optional<T>, @Nullable T>comparing(
        o -> orElseNull(o), Comparator.nullsLast(valueComparator));
  }

  // For discussion of why this exists, see the Android flavor.
  private static <T> @Nullable T orElseNull(Optional<T> optional) {
    return optional.orElse(null);
  }

  /**

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

/**
 * Implementation of {@link Multimaps#filterKeys(SetMultimap, Predicate)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
final class FilteredKeySetMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends FilteredKeyMultimap<K, V> implements FilteredSetMultimap<K, V> {

import com.google.common.annotations.J2ktIncompatible;
import java.io.Serializable;
import java.util.Iterator;
import org.jspecify.annotations.Nullable;

@GwtCompatible
final class PairwiseEquivalence<E, T extends @Nullable E> extends Equivalence<Iterable<T>>
    implements Serializable {
  final Equivalence<E> elementEquivalence;

  PairwiseEquivalence(Equivalence<E> elementEquivalence) {

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

/**
 * Creates sets, containing sample elements, to be tested.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@NullMarked
public interface TestSetGenerator<E extends @Nullable Object> extends TestCollectionGenerator<E> {
  @Override
  Set<E> create(Object... elements);

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

/**
 * Creates sets, containing sample elements, to be tested.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@NullMarked
public interface TestSetGenerator<E extends @Nullable Object> extends TestCollectionGenerator<E> {
  @Override
  Set<E> create(Object... elements);

import static java.util.Collections.shuffle;

import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Package up sample data for common collections benchmarking.
 *
 * @author Nicholaus Shupe
 */
@NullUnmarked
class CollectionBenchmarkSampleData {
  private final boolean isUserTypeFast;

import org.jspecify.annotations.Nullable;

/**
 * This class provides a skeletal implementation of the {@link ListIterator} interface across a
 * fixed number of elements that may be retrieved by position. It does not support {@link #remove},
 * {@link #set}, or {@link #add}.
 *
 * @author Jared Levy
 */
@GwtCompatible
abstract class AbstractIndexedListIterator<E extends @Nullable Object>
    extends UnmodifiableListIterator<E> {