class RatesCurveGroup implements CurveGroup, ImmutableBean, Serializable {

  @Override
  public Stream<Curve> stream() {
    return Stream.concat(discountCurves.values().stream(), forwardCurves.values().stream());
  }

  private  RatesCurveGroup(
      CurveGroupName name,
      Map<Currency, Curve> discountCurves,
      Map<? extends Index, ? extends Curve> forwardCurves);

}