* @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible
public abstract class ForwardingMapEntry<K extends @Nullable Object, V extends @Nullable Object>
    extends ForwardingObject implements Map.Entry<K, V> {
  // TODO(lowasser): identify places where thread safety is actually lost

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

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

  @Override

 * @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible
public abstract class ForwardingMapEntry<K extends @Nullable Object, V extends @Nullable Object>
    extends ForwardingObject implements Map.Entry<K, V> {
  // TODO(lowasser): identify places where thread safety is actually lost

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

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

  @Override

   */
  private static <B extends @Nullable Object> Entry<Class<? extends @NonNull B>, B> checkedEntry(
      Entry<Class<? extends @NonNull B>, B> entry) {
    return new ForwardingMapEntry<Class<? extends @NonNull B>, B>() {
      @Override
      protected Entry<Class<? extends @NonNull B>, B> delegate() {
        return entry;
      }

      @Override
      @ParametricNullness

   */
  private static <B extends @Nullable Object> Entry<Class<? extends @NonNull B>, B> checkedEntry(
      Entry<Class<? extends @NonNull B>, B> entry) {
    return new ForwardingMapEntry<Class<? extends @NonNull B>, B>() {
      @Override
      protected Entry<Class<? extends @NonNull B>, B> delegate() {
        return entry;
      }

      @Override
      @ParametricNullness

    TestMap<K, V> inner = new TestMap<>(innermost, mutex);
    NavigableMap<K, V> outer = Synchronized.navigableMap(inner, mutex);
    return outer;
  }

  static class TestEntry<K, V> extends ForwardingMapEntry<K, V> implements Serializable {
    private final Entry<K, V> delegate;
    private final Object mutex;

    TestEntry(Entry<K, V> delegate, Object mutex) {
      this.delegate = delegate;
      this.mutex = mutex;

  @Override
  public Set<Entry<K, V>> entrySet() {
    Set<Entry<K, V>> result = entrySet;
    return (result == null) ? entrySet = new EntrySet() : result;
  }

  private final class BiMapEntry extends ForwardingMapEntry<K, V> {
    private final Entry<K, V> delegate;

    BiMapEntry(Entry<K, V> delegate) {
      this.delegate = delegate;
    }

    @Override
    protected Entry<K, V> delegate() {

  @Override
  public Set<Entry<K, V>> entrySet() {
    Set<Entry<K, V>> result = entrySet;
    return (result == null) ? entrySet = new EntrySet() : result;
  }

  private final class BiMapEntry extends ForwardingMapEntry<K, V> {
    private final Entry<K, V> delegate;

    BiMapEntry(Entry<K, V> delegate) {
      this.delegate = delegate;
    }

    @Override
    protected Entry<K, V> delegate() {

          backingRowMap.entrySet().spliterator(),
          Spliterator.DISTINCT | Spliterator.NONNULL,
          this::wrapEntry);
    }

    Entry<C, V> wrapEntry(Entry<C, V> entry) {
      return new ForwardingMapEntry<C, V>() {
        @Override
        protected Entry<C, V> delegate() {
          return entry;
        }

        @Override
        public V setValue(V value) {

        public void remove() {
          iterator.remove();
          maintainEmptyInvariant();
        }
      };
    }

    Entry<C, V> wrapEntry(Entry<C, V> entry) {
      return new ForwardingMapEntry<C, V>() {
        @Override
        protected Entry<C, V> delegate() {
          return entry;
        }

        @Override
        public V setValue(V value) {

          super.iterator()) {
        @Override
        Map.Entry<K, Collection<V>> transform(Map.Entry<K, Collection<V>> entry) {
          return new ForwardingMapEntry<K, Collection<V>>() {
            @Override
            protected Map.Entry<K, Collection<V>> delegate() {
              return entry;
            }

            @Override