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