* {@link ForwardingMultiset#clear}, {@link ForwardingMultiset#contains}, {@link
   * ForwardingMultiset#containsAll}, {@link ForwardingMultiset#count}, {@link
   * ForwardingMultiset#isEmpty}, the {@link Set#size} and {@link Set#iterator} methods of {@link
   * ForwardingMultiset#entrySet}, and {@link ForwardingMultiset#remove(Object, int)}. In many

   * {@link ForwardingMultiset#clear}, {@link ForwardingMultiset#contains}, {@link
   * ForwardingMultiset#containsAll}, {@link ForwardingMultiset#count}, {@link
   * ForwardingMultiset#isEmpty}, the {@link Set#size} and {@link Set#iterator} methods of {@link
   * ForwardingMultiset#entrySet}, and {@link ForwardingMultiset#remove(Object, int)}. In many

import org.jspecify.annotations.Nullable;

/**
 * Tests for {@link ForwardingMultiset}.
 *
 * @author Hayward Chan
 * @author Louis Wasserman
 */
@NullUnmarked
public class ForwardingMultisetTest extends TestCase {

  static final class StandardImplForwardingMultiset<T> extends ForwardingMultiset<T> {
    private final Multiset<T> backingCollection;

 * {@code entryIterator()}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
abstract class DescendingMultiset<E extends @Nullable Object> extends ForwardingMultiset<E>
    implements SortedMultiset<E> {
  abstract SortedMultiset<E> forwardMultiset();

  @LazyInit private transient @Nullable Comparator<? super E> comparator;

  @Override

 * {@code entryIterator()}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
abstract class DescendingMultiset<E extends @Nullable Object> extends ForwardingMultiset<E>
    implements SortedMultiset<E> {
  abstract SortedMultiset<E> forwardMultiset();

  @Nullable private transient Comparator<? super E> comparator;

  @Override
  public Comparator<? super E> comparator() {

 * {@code entryIterator()}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
abstract class DescendingMultiset<E extends @Nullable Object> extends ForwardingMultiset<E>
    implements SortedMultiset<E> {
  abstract SortedMultiset<E> forwardMultiset();

  @LazyInit private transient @Nullable Comparator<? super E> comparator;

  @Override

 *
 * @author Louis Wasserman
 * @since 15.0
 */
@GwtCompatible
public abstract class ForwardingSortedMultiset<E extends @Nullable Object>
    extends ForwardingMultiset<E> implements SortedMultiset<E> {
  /** Constructor for use by subclasses. */
  protected ForwardingSortedMultiset() {}

  @Override
  protected abstract SortedMultiset<E> delegate();

  @Override

 * thread-safe, even when all of the methods that they depend on are thread-safe.
 *
 * @author Louis Wasserman
 */
public abstract class ForwardingSortedMultiset<E extends @Nullable Object>
    extends ForwardingMultiset<E> implements SortedMultiset<E> {
  /** Constructor for use by subclasses. */
  protected ForwardingSortedMultiset() {}

  @Override
  protected abstract SortedMultiset<E> delegate();

  @Override

 *
 * @author Louis Wasserman
 * @since 15.0
 */
@GwtCompatible
public abstract class ForwardingSortedMultiset<E extends @Nullable Object>
    extends ForwardingMultiset<E> implements SortedMultiset<E> {
  /** Constructor for use by subclasses. */
  protected ForwardingSortedMultiset() {}

  @Override
  protected abstract SortedMultiset<E> delegate();

  @Override

  @Deprecated
  public static <E> Multiset<E> unmodifiableMultiset(ImmutableMultiset<E> multiset) {
    return checkNotNull(multiset);
  }

  static class UnmodifiableMultiset<E extends @Nullable Object> extends ForwardingMultiset<E>
      implements Serializable {
    final Multiset<? extends E> delegate;

    UnmodifiableMultiset(Multiset<? extends E> delegate) {
      this.delegate = delegate;
    }