Metrics constructor Null safety

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

Metrics class

1. Constructors
2. Metrics
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Static properties
12. current
13. Static methods
14. deregister
15. register