Failed to create JSON from YAML if OpenApi specs contains property names that are Dart keywords

[ASKabanets]

Example to handle:
`
@freezed()
class OperatorStringIs with _$OperatorStringIs {
const factory OperatorStringIs({
/// The name has been replaced because it contains a keyword. Original name: 'is'.
@jsonkey(name: 'is')
required String isValue,
}) = _OperatorStringIs;

}`