initialize static method Null safety

1. baguette
2. UnitTests
3. UnitTests
4. initialize static method

UnitTests class

1. Constructors
2. UnitTests
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Static methods
12. initialize
13. maxWait
14. mediumWait
15. minWait
16. wait
17. Constants
18. WAIT_DURATION_MAX
19. WAIT_DURATION_MEDIUM
20. WAIT_DURATION_MIN