kind property Null safety

1. mapbox_maps_flutter
2. mapbox_maps_flutter
3. Request
4. kind property

Request class

1. Constructors
2. fromJson
3. Properties
4. hashCode
5. kind
6. loadingMethod
7. priority
8. runtimeType
9. url
10. Methods
11. noSuchMethod
12. toString
13. Operators
14. operator ==