subscribe method Null safety

1. baguette
2. LocationManager
3. LocationManager
4. subscribe method

LocationManager class

1. Constructors
2. LocationManager
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. addPlugin
8. cleanPlugins
9. getLocation
10. getPlugin
11. noSuchMethod
12. removePlugin
13. subscribe
14. toString
15. unsubscribe
16. Operators
17. operator ==