*
   * <p>Note that if {@code s} is a {@code Set<String>}, then {@code ImmutableSortedSet.copyOf(s)}
   * returns an {@code ImmutableSortedSet<String>} containing each of the strings in {@code s},
   * while {@code ImmutableSortedSet.of(s)} returns an {@code ImmutableSortedSet<Set<String>>}
   * containing one element (the given set itself).
   *

   *
   * <p>Note that if {@code s} is a {@code Set<String>}, then {@code ImmutableSortedSet.copyOf(s)}
   * returns an {@code ImmutableSortedSet<String>} containing each of the strings in {@code s},
   * while {@code ImmutableSortedSet.of(s)} returns an {@code ImmutableSortedSet<Set<String>>}
   * containing one element (the given set itself).
   *

/**
 * GWT emulation of {@link com.google.common.collect.ImmutableSortedSet}.
 *
 * @author Hayward Chan
 */
@ElementTypesAreNonnullByDefault
public abstract class ImmutableSortedSet<E> extends ForwardingImmutableSet<E>
    implements SortedSet<E>, SortedIterable<E> {
  // TODO(cpovirk): split into ImmutableSortedSet/ForwardingImmutableSortedSet?

        Equivalence.equals()
            .onResultOf(ImmutableSortedSet<String>::comparator)
            .and(Equivalence.equals().onResultOf(ImmutableSortedSet::asList))
            .and(Equivalence.equals());
    CollectorTester.of(collector, equivalence)
        .expectCollects(
            ImmutableSortedSet.of("a", "b", "c", "d"), "a", "b", "a", "c", "b", "b", "d");
  }

    // Note that a Collector should generally enforce consistent comparator between builders
    ImmutableSortedSet.Builder<String> zis =
        ImmutableSortedSet.<String>naturalOrder().add("c", "b", "c");
    ImmutableSortedSet.Builder<String> zat =
        ImmutableSortedSet.<String>naturalOrder().add("a", "b", "d", "c");
    ImmutableSortedSet<String> sortedSet = zis.combine(zat).build();

  }

  static <E> Collector<E, ?, ImmutableSortedSet<E>> toImmutableSortedSet(
      Comparator<? super E> comparator) {
    checkNotNull(comparator);
    return Collector.of(
        () -> new ImmutableSortedSet.Builder<E>(comparator),
        ImmutableSortedSet.Builder::add,
        ImmutableSortedSet.Builder::combine,
        ImmutableSortedSet.Builder::build);
  }

    assertTrue(multimap.get("a") instanceof ImmutableSortedSet);
    assertEquals(
        Collections.reverseOrder(), ((ImmutableSortedSet<Integer>) multimap.get("a")).comparator());
    assertTrue(multimap.get("x") instanceof ImmutableSortedSet);
    assertEquals(
        Collections.reverseOrder(), ((ImmutableSortedSet<Integer>) multimap.get("x")).comparator());

/**
 * Skeletal implementation of {@link ImmutableSortedSet#descendingSet()}.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault
final class DescendingImmutableSortedSet<E> extends ImmutableSortedSet<E> {
  private final ImmutableSortedSet<E> forward;

  DescendingImmutableSortedSet(ImmutableSortedSet<E> forward) {
    super(Ordering.from(forward.comparator()).reverse());

      return ImmutableSortedSet.copyOf(elements);
    }
  }

  public static class ImmutableSortedSetHeadsetGenerator extends TestStringSortedSetGenerator {
    @Override
    protected SortedSet<String> create(String[] elements) {
      List<String> list = Lists.newArrayList(elements);
      list.add("zzz");
      return ImmutableSortedSet.copyOf(list).headSet("zzy");
    }
  }

            .build();

    assertThat(RANGE_SET_ONE.difference(RANGE_SET_TWO)).isEqualTo(expected);
  }

  public void testAsSet() {
    ImmutableSortedSet<Integer> expectedSet = ImmutableSortedSet.of(2, 3, 4, 8, 9, 16, 17);
    ImmutableSortedSet<Integer> asSet = RANGE_SET_ONE.asSet(DiscreteDomain.integers());
    assertEquals(expectedSet, asSet);
    assertThat(asSet).containsExactlyElementsIn(expectedSet).inOrder();