call method

  1. @override
String? call(
  1. T? value
)
override

Implementation

@override
String? call(T? value) {
  if (value is String && value.isEmpty) {
    return 'Requires a value';
  }
  if (value == null) {
    return 'Requires a value';
  } else {
    return null;
  }
}