private void listSubdomains(
      @Nonnull ProviderContext ctx,
      @Nonnull List<DNSZone> intoList,
      @Nonnull DNSZone parent,
      @Nonnull JSONArray subdomains)
      throws CloudException, InternalException {
    try {
      for (int i = 0; i < subdomains.length(); i++) {
        DNSZone z = toZone(ctx, subdomains.getJSONObject(i));

        if (z != null) {
          z.setNameservers(parent.getNameservers());
          intoList.add(z);
        }
      }
    } catch (JSONException e) {
      throw new CloudException(e);
    }
  }