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

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

  @Override