@GwtCompatible
@ElementTypesAreNonnullByDefault
abstract class AbstractSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMapBasedMultimap<K, V> implements SetMultimap<K, V> {
  /**
   * Creates a new multimap that uses the provided map.
   *
   * @param map place to store the mapping from each key to its corresponding values
   */
  protected AbstractSetMultimap(Map<K, Collection<V>> map) {
    super(map);
  }

@GwtCompatible
@ElementTypesAreNonnullByDefault
abstract class AbstractSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMapBasedMultimap<K, V> implements SetMultimap<K, V> {
  /**
   * Creates a new multimap that uses the provided map.
   *
   * @param map place to store the mapping from each key to its corresponding values
   */
  protected AbstractSetMultimap(Map<K, Collection<V>> map) {
    super(map);
  }

 *
 * @author Jared Levy
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
abstract class AbstractSortedSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractSetMultimap<K, V> implements SortedSetMultimap<K, V> {
  /**
   * Creates a new multimap that uses the provided map.
   *
   * @param map place to store the mapping from each key to its corresponding values
   */

    return new CustomSetMultimap<>(map, factory);
  }

  private static class CustomSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
      extends AbstractSetMultimap<K, V> {
    transient Supplier<? extends Set<V>> factory;

    CustomSetMultimap(Map<K, Collection<V>> map, Supplier<? extends Set<V>> factory) {
      super(map);
      this.factory = checkNotNull(factory);