SortedMap<String, String> map = populate(new TreeMap<String, String>(), entries);
                return Collections.checkedSortedMap(map, String.class, String.class);
              }
            })
        .named("checkedSortedMap/TreeMap, natural")
        .withFeatures(
            MapFeature.GENERAL_PURPOSE,
            MapFeature.ALLOWS_NULL_VALUES,