issuingCountryListToJson function
Implementation
List<String> issuingCountryListToJson(
    List<enums.IssuingCountry>? issuingCountry) {
  if (issuingCountry == null) {
    return [];
  }
  return issuingCountry.map((e) => enums.$IssuingCountryMap[e]!).toList();
}