display method
Implementation
@override
String display() {
final fields = _fields.map(
(entry) {
final sb = StringBuffer(entry.key);
if (entry.value.name.isNotEmpty && entry.value.name != 'null') {
sb.write(':${entry.value.display()}');
}
return sb.toString();
},
);
return "variant {${fields.join('; ')}}";
}