offset property Null safety

1. jrpn
2. model
3. ShiftKey
4. offset property

ShiftKey class

1. Properties
2. hashCode
3. name
4. offset
5. runtimeType
6. select
7. Methods
8. noSuchMethod
9. toString
10. Operators
11. operator ==
12. Static properties
13. f
14. g
15. none