* @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class ForwardingConcurrentMap<K, V> extends ForwardingMap<K, V>
    implements ConcurrentMap<K, V> {

  /** Constructor for use by subclasses. */
  protected ForwardingConcurrentMap() {}

  @Override
  protected abstract ConcurrentMap<K, V> delegate();

  @CanIgnoreReturnValue
  @Override
  @CheckForNull

  }

  private final transient SortedSet<E> sortedDelegate;

  /**
   * Scary constructor for ContiguousSet. This constructor (in this file, the GWT emulation of
   * ImmutableSortedSet) creates an empty sortedDelegate, which, in a vacuum, sets this object's
   * contents to empty. By contrast, the non-GWT constructor with the same signature uses the

  @RetainedWith
  transient AbstractBiMap<V, K> inverse;

  /** Package-private constructor for creating a map-backed bimap. */
  AbstractBiMap(Map<K, V> forward, Map<V, K> backward) {
    setDelegates(forward, backward);
  }

  /** Private constructor for inverse bimap. */
  private AbstractBiMap(Map<K, V> backward, AbstractBiMap<V, K> forward) {
    delegate = backward;

 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class ForwardingMultiset<E extends @Nullable Object> extends ForwardingCollection<E>
    implements Multiset<E> {

  /** Constructor for use by subclasses. */
  protected ForwardingMultiset() {}

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

  @Override
  public int count(@CheckForNull Object element) {

 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class ForwardingListIterator<E extends @Nullable Object>
    extends ForwardingIterator<E> implements ListIterator<E> {

  /** Constructor for use by subclasses. */
  protected ForwardingListIterator() {}

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

  @Override
  public void add(@ParametricNullness E element) {

import com.google.common.collect.testing.features.CollectionSize;
import java.lang.reflect.Method;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests creation (typically through a constructor or static factory
 * method) of a collection. Can't be invoked directly; please see {@link
 * com.google.common.collect.testing.CollectionTestSuiteBuilder}.
 *
 * @author Chris Povirk
 */
@GwtCompatible(emulated = true)

 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class ForwardingConcurrentMap<K, V> extends ForwardingMap<K, V>
    implements ConcurrentMap<K, V> {

  /** Constructor for use by subclasses. */
  protected ForwardingConcurrentMap() {}

  @Override
  protected abstract ConcurrentMap<K, V> delegate();

  @CanIgnoreReturnValue
  @Override
  @CheckForNull

 * good reference implementation. As with {@code IteratorTester}, a concrete subclass must provide
 * target iterators on demand. It also requires three additional constructor parameters: {@code
 * elementsToInsert}, the elements to be passed to {@code set()} and {@code add()} calls; {@code
 * features}, the features supported by the iterator; and {@code expectedElements}, the elements the

@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class ForwardingListMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends ForwardingMultimap<K, V> implements ListMultimap<K, V> {

  /** Constructor for use by subclasses. */
  protected ForwardingListMultimap() {}

  @Override
  protected abstract ListMultimap<K, V> delegate();

  @Override
  public List<V> get(@ParametricNullness K key) {

 * single-element enum to maintain serialization guarantees. See Effective Java (2nd Edition), Item
 * 3: "Enforce the singleton property with a private constructor or an enum type". For example:
 *
 * <pre>{@code
 * public enum PersonFunnel implements Funnel<Person> {
 *   INSTANCE;
 *   public void funnel(Person person, PrimitiveSink into) {