* AbstractMapBasedMultimap} that converts the returned collections into {@code Sets}. The {@link
 * #createCollection} method must return a {@code Set}.
 *
 * @author Jared Levy
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
abstract class AbstractSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMapBasedMultimap<K, V> implements SetMultimap<K, V> {
  /**

 * AbstractMapBasedMultimap} that converts the returned collections into {@code Sets}. The {@link
 * #createCollection} method must return a {@code Set}.
 *
 * @author Jared Levy
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
abstract class AbstractSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMapBasedMultimap<K, V> implements SetMultimap<K, V> {
  /**

import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Basic implementation of the {@link SortedSetMultimap} interface. It's a wrapper around {@link
 * AbstractMapBasedMultimap} that converts the returned collections into sorted sets. The {@link
 * #createCollection} method must return a {@code SortedSet}.
 *
 * @author Jared Levy
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault

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

  private static class CustomMultimap<K extends @Nullable Object, V extends @Nullable Object>
      extends AbstractMapBasedMultimap<K, V> {
    transient Supplier<? extends Collection<V>> factory;

    CustomMultimap(Map<K, Collection<V>> map, Supplier<? extends Collection<V>> factory) {
      super(map);