Using union instead of knownvalues decorator in below case

[situ311417]

How to use union in place of knownvalues decorator
1st case
Model debit{

@knownvalues(cardstatus)
OrderType: string;
}
Enum cardstatus{
Initial,
Reorder
}

2nd case

@knownvalues(countrycode)
Maxlength(10)
Minlength(5)
Scalar isocountry extends string;

Enum countrycode {
Aed,
Ind,
Aus,
Usa}

Please suggest

[situ311417]

@timotheeguerin can you please help on this