ImmutableSortedMap::copyOfSorted);
  }

  // unsafe, comparator() returns a comparator on the specified type
  @SuppressWarnings("unchecked")
  public static <K, V> ImmutableSortedMap<K, V> of() {
    return new Builder<K, V>((Comparator<K>) NATURAL_ORDER).build();
  }

  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(K k1, V v1) {

          .put(Map.class, ImmutableMap.of())
          .put(ImmutableMap.class, ImmutableMap.of())
          .put(SortedMap.class, ImmutableSortedMap.of())
          .put(ImmutableSortedMap.class, ImmutableSortedMap.of())
          .put(NavigableMap.class, Maps.unmodifiableNavigableMap(Maps.newTreeMap()))
          .put(Multimap.class, ImmutableMultimap.of())

     */
    return Collector.of(
        () -> new ImmutableSortedMap.Builder<K, V>(comparator),
        (builder, input) -> builder.put(keyFunction.apply(input), valueFunction.apply(input)),
        ImmutableSortedMap.Builder::combine,
        ImmutableSortedMap.Builder::buildOrThrow,
        Collector.Characteristics.UNORDERED);
  }

     */
    return Collector.of(
        () -> new ImmutableSortedMap.Builder<K, V>(comparator),
        (builder, input) -> builder.put(keyFunction.apply(input), valueFunction.apply(input)),
        ImmutableSortedMap.Builder::combine,
        ImmutableSortedMap.Builder::buildOrThrow,
        Collector.Characteristics.UNORDERED);
  }

  // Creation tests

  public void testEmptyBuilder() {
    ImmutableSortedMap<String, Integer> map =
        ImmutableSortedMap.<String, Integer>naturalOrder().build();
    assertEquals(Collections.<String, Integer>emptyMap(), map);
  }

  public void testSingletonBuilder() {
    ImmutableSortedMap<String, Integer> map =
        ImmutableSortedMap.<String, Integer>naturalOrder().put("one", 1).build();

  public static class ImmutableSortedMapGenerator extends TestStringSortedMapGenerator {
    @Override
    public SortedMap<String, String> create(Entry<String, String>[] entries) {
      ImmutableSortedMap.Builder<String, String> builder = ImmutableSortedMap.naturalOrder();
      for (Entry<String, String> entry : entries) {
        checkNotNull(entry);
        builder.put(entry.getKey(), entry.getValue());
      }
      return builder.build();

  public static class ImmutableSortedMapGenerator extends TestStringSortedMapGenerator {
    @Override
    public SortedMap<String, String> create(Entry<String, String>[] entries) {
      ImmutableSortedMap.Builder<String, String> builder = ImmutableSortedMap.naturalOrder();
      for (Entry<String, String> entry : entries) {
        checkNotNull(entry);
        builder.put(entry.getKey(), entry.getValue());
      }
      return builder.build();

@NullUnmarked
public class SingletonImmutableSortedMapMapInterfaceTest
    extends AbstractImmutableSortedMapMapInterfaceTest<String, Integer> {
  @Override
  protected SortedMap<String, Integer> makePopulatedMap() {
    return ImmutableSortedMap.of("one", 1);
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "minus one";
  }

  @Override
  protected Integer getValueNotInPopulatedMap() {
    return -1;
  }

                  @Override
                  protected SortedMap<String, String> create(Entry<String, String>[] entries) {
                    ImmutableSortedMap.Builder<String, String> builder =
                        ImmutableSortedMap.naturalOrder();
                    for (Entry<String, String> entry : entries) {
                      builder.put(entry.getKey(), entry.getValue());
                    }

    extends AbstractImmutableSortedMapMapInterfaceTest<String, Integer> {
  @Override
  protected SortedMap<String, Integer> makeEmptyMap() {
    return ImmutableSortedMap.of();
  }

  @Override
  protected SortedMap<String, Integer> makePopulatedMap() {
    return ImmutableSortedMap.of("one", 1, "two", 2, "three", 3);
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "minus one";
  }

  @Override