forward method
Appends this flag to out if it was explicitly passed.
Values are emitted as separate --name value tokens so a value that
itself contains = (--dart-define BASE_URL=https://…) stays
unambiguous.
Implementation
@override
void forward(ArgResults results, List<String> out) {
if (results.wasParsed(name) && (results[name] as bool? ?? false)) {
out.add('--$name');
}
}