StackTraceMapper constructor Null safety

1. Flutter
2. test_api.backend
3. StackTraceMapper
4. StackTraceMapper constructor

StackTraceMapper class

1. Constructors
2. StackTraceMapper
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. mapStackTrace
8. noSuchMethod
9. serialize
10. toString
11. Operators
12. operator ==