.withFeatures(
                MapFeature.ALLOWS_NULL_KEYS,
                MapFeature.ALLOWS_NULL_VALUES,
                MapFeature.ALLOWS_ANY_NULL_QUERIES,
                MapFeature.GENERAL_PURPOSE,
                CollectionSize.ANY)
            .createTestSuite());
    suite.addTest(
        MapTestSuiteBuilder.using(
                new TestStringMapGenerator() {
                  @Override

            .withFeatures(
                MapFeature.ALLOWS_NULL_KEYS,
                MapFeature.ALLOWS_NULL_VALUES,
                MapFeature.ALLOWS_ANY_NULL_QUERIES,
                MapFeature.GENERAL_PURPOSE,
                MapFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION,
                CollectionFeature.SUPPORTS_ITERATOR_REMOVE,
                CollectionSize.ANY)
            .createTestSuite());

                return new ArrayList<>(MinimalCollection.of(elements));
              }
            })
        .named("ArrayList")
        .withFeatures(
            ListFeature.GENERAL_PURPOSE,
            CollectionFeature.SERIALIZABLE,
            CollectionFeature.ALLOWS_NULL_VALUES,
            CollectionFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION,
            CollectionSize.ANY)

                return new ArrayList<>(MinimalCollection.of(elements));
              }
            })
        .named("ArrayList")
        .withFeatures(
            ListFeature.GENERAL_PURPOSE,
            CollectionFeature.SERIALIZABLE,
            CollectionFeature.ALLOWS_NULL_VALUES,
            CollectionFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION,
            CollectionSize.ANY)

 *
 * @author George van den Driessche
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible
public enum SetFeature implements Feature<Set> {
  GENERAL_PURPOSE(CollectionFeature.GENERAL_PURPOSE);

  private final Set<Feature<? super Set>> implied;

  SetFeature(Feature<? super Set>... implied) {
    this.implied = copyToSet(implied);
  }

  @Override

@GwtCompatible
public enum ListFeature implements Feature<List> {
  SUPPORTS_SET,
  SUPPORTS_ADD_WITH_INDEX(CollectionFeature.SUPPORTS_ADD),
  SUPPORTS_REMOVE_WITH_INDEX(CollectionFeature.SUPPORTS_REMOVE),

  GENERAL_PURPOSE(
      CollectionFeature.GENERAL_PURPOSE,
      SUPPORTS_SET,
      SUPPORTS_ADD_WITH_INDEX,
      SUPPORTS_REMOVE_WITH_INDEX),

  /** Features supported by lists where only removal is allowed. */

      WrappedHashMapGenerator generator, String name, Feature<?>... features) {
    List<Feature<?>> featuresList = Lists.newArrayList(features);
    Collections.addAll(
        featuresList,
        MapFeature.GENERAL_PURPOSE,
        CollectionFeature.SUPPORTS_ITERATOR_REMOVE,
        CollectionSize.ANY);
    return MapTestSuiteBuilder.using(generator)
        .named(name)
        .withFeatures(featuresList)
        .createTestSuite();

   * {@link IllegalArgumentException} when presented with duplicate keys instead of discarding all
   * but one.
   */
  REJECTS_DUPLICATES_AT_CREATION,

  GENERAL_PURPOSE(SUPPORTS_PUT, SUPPORTS_REMOVE);

  private final Set<Feature<? super Map>> implied;

  MapFeature(Feature<? super Map>... implied) {
    this.implied = copyToSet(implied);
  }

  @Override

              CollectionFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION)
          .put(MapFeature.GENERAL_PURPOSE, ListFeature.SUPPORTS_ADD_WITH_INDEX)
          .put(MapFeature.GENERAL_PURPOSE, ListFeature.SUPPORTS_REMOVE_WITH_INDEX)
          .put(MapFeature.GENERAL_PURPOSE, ListFeature.SUPPORTS_SET)
          .put(MapFeature.ALLOWS_NULL_VALUE_QUERIES, CollectionFeature.ALLOWS_NULL_QUERIES)

                CollectionFeature.SERIALIZABLE,
                MapFeature.ALLOWS_NULL_VALUES,
                CollectionFeature.SUPPORTS_ITERATOR_REMOVE,
                MapFeature.GENERAL_PURPOSE)
            .named("SafeTreeMap with natural comparator")
            .createTestSuite());
    suite.addTest(
        NavigableMapTestSuiteBuilder.using(
                new TestStringSortedMapGenerator() {