Timing constructor Null safety

1. wings_data_model
2. wings_data_model
3. Timing
4. Timing factory constructor

Timing class

1. Constructors
2. Timing
3. Properties
4. code
5. event
6. hashCode
7. id
8. runtimeType
9. Methods
10. noSuchMethod
11. rebuild
12. toBuilder
13. toString
14. Operators
15. operator ==