plural method
Return the translation of plural key provided
Implementation
String plural() {
final Map<dynamic, dynamic> decodedSubMap = calculateSubmap(key);
key = _findCorrectKey(decodedSubMap);
final String? parameterName = _findParameterName(decodedSubMap);
translationParams =
Map.fromIterables([parameterName], [pluralValue.toString()]);
return translate();
}