location property Null safety

1. Flutter
2. vm_service
3. Message
4. location property

Message class

1. Constructors
2. Message
3. Properties
4. handler
5. hashCode
6. index
7. json
8. location
9. messageObjectId
10. name
11. runtimeType
12. size
13. type
14. Methods
15. noSuchMethod
16. toJson
17. toString
18. Operators
19. operator ==
20. Static methods
21. parse