Password.pure constructor Null safety

1. univalle_app
2. sign_in
3. Password
4. Password.pure const constructor

Password class

1. Constructors
2. dirty
3. pure
4. Properties
5. error
6. hashCode
7. invalid
8. pure
9. runtimeType
10. status
11. valid
12. value
13. Methods
14. noSuchMethod
15. toString
16. validator
17. Operators
18. operator ==