generateNonce method
Implementation
String generateNonce([int length = 32]) {
const charset = '0123456789ABCDEFGHIJKLMNOPQRSTUVXYZabcdefghijklmnopqrstuvwxyz-._';
final random = Random.secure();
return List.generate(length, (_) => charset[random.nextInt(charset.length)]).join();
}