key property Null safety

1. farmershands
2. weather_service
3. WeatherService
4. key property

WeatherService class

1. Constructors
2. WeatherService
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Static properties
12. dateFormat
13. decodingKey
14. endPoint
15. key
16. Static methods
17. baseTime
18. getTodayWeather
19. skyState