isRaceDay property Null safety

1. irte_engine
2. race_day_controller
3. RaceDayController
4. isRaceDay property

RaceDayController class

1. Constructors
2. RaceDayController
3. Properties
4. canStartRace
5. completion
6. container
7. countdown
8. emitMinorEvents
9. events
10. hashCode
11. hasListeners
12. initialized
13. isClosed
14. isRaceDay
15. lastEvent
16. listeners
17. milestones
18. minorEvents
19. onDelete
20. onStart
21. raceStart
22. registry
23. repeats
24. runtimeType
25. state
26. withMilestones
27. Methods
28. $configureLifeCycle
29. addListener
30. addListenerId
31. changeState
32. dispose
33. disposeId
34. executeListeners
35. initCountdown
36. noSuchMethod
37. notifyChildrens
38. onceState
39. onClose
40. onInit
41. onReady
42. refresh
43. refreshGroup
44. registerListenerPlugin
45. removeListener
46. removeListenerId
47. toString
48. update
49. updateRaceStatus
50. Operators
51. operator ==
52. Static properties
53. instance