@Override
              public NavigableSet<String> create(String[] elements) {
                NavigableSet<String> innerSet = new TreeSet<>();
                Collections.addAll(innerSet, elements);
                return Collections.checkedNavigableSet(innerSet, String.class);
              }
            })
        .named("checkedNavigableSet/TreeSet, natural")
        .withFeatures(

            new TestStringSetGenerator() {
              @Override
              public Set<String> create(String[] elements) {
                Set<String> innerSet = new HashSet<>();
                Collections.addAll(innerSet, elements);
                return unmodifiableSet(innerSet);
              }
            })
        .named("unmodifiableSet/HashSet")
        .withFeatures(
            CollectionFeature.NONE,