id property Null safety

1. Flutter
2. vm_service
3. OpenFileRef
4. id property

OpenFileRef class

1. Constructors
2. OpenFileRef
3. Properties
4. hashCode
5. id
6. name
7. runtimeType
8. Methods
9. noSuchMethod
10. toString
11. Operators
12. operator ==
13. Static methods
14. parse
15. Constants
16. type