copy method
Implementation
UserModel copy([Map<String, dynamic>? json]) => UserModel(
id: json.asOrNull<int>('id') ?? id,
name: json.asOrNull<String>('name') ?? name,
email: json.asOrNull<String>('email') ?? email,
password: json.asOrNull<String>('password')?.asMD5() ?? password,
role: json.asOrNull<UserRole>('role') ?? role,
);