expandedKeys method
Implementation
@override
List<String> expandedKeys(String key) {
var exp = <String>[
key,
if (key.contains('-')) key.replaceAll('-', '_'),
if (key.contains('_')) key.replaceAll('_', '-'),
];
exp.addAll(exp.map((k) => k.toUpperCase()).toList());
exp.addAll(exp.map((k) => k.toLowerCase()).toList());
var norm = exp.expand(normalizedKeys).toList();
var allExp = <String>[...exp, ...norm];
return allExp;
}