* {@link Multiset#entrySet()}, as do many methods acting on the set returned by {@link
 * #elementSet()}. Override those methods for better performance.
 *
 * @author Kevin Bourrillion
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
abstract class AbstractMultiset<E extends @Nullable Object> extends AbstractCollection<E>
    implements Multiset<E> {
  // Query Operations

  @Override

 * {@link Multiset#entrySet()}, as do many methods acting on the set returned by {@link
 * #elementSet()}. Override those methods for better performance.
 *
 * @author Kevin Bourrillion
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
abstract class AbstractMultiset<E extends @Nullable Object> extends AbstractCollection<E>
    implements Multiset<E> {
  // Query Operations

  @Override