Timeline constructor Null safety

1. Dart
2. dart:developer
3. Timeline
4. Timeline constructor

Timeline class

1. Constructors
2. Timeline
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Static properties
12. now
13. Static methods
14. finishSync
15. instantSync
16. startSync
17. timeSync