public Enums() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super(AnEnum.B, AnEnum.A, AnEnum.C, AnEnum.D, AnEnum.E);
    }
  }

  public static class Ints extends SampleElements<Integer> {
    public Ints() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super(1, 0, 2, 3, 4);
    }
  }

  public static <K extends @Nullable Object, V extends @Nullable Object>

    public Enums() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super(AnEnum.B, AnEnum.A, AnEnum.C, AnEnum.D, AnEnum.E);
    }
  }

  public static class Ints extends SampleElements<Integer> {
    public Ints() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super(1, 0, 2, 3, 4);
    }
  }

  public static <K extends @Nullable Object, V extends @Nullable Object>