password property Null safety

1. irte_engine
2. user.model
3. User
4. password property

User class

1. Constructors
2. User
3. empty
4. fromJson
5. Properties
6. email
7. firstname
8. hashCode
9. id
10. isValid
11. lastname
12. password
13. runtimeType
14. Methods
15. noSuchMethod
16. toJson
17. toString
18. Operators
19. operator ==