PrefsConstants constructor Null safety

1. farmershands
2. prefs_constants
3. PrefsConstants
4. PrefsConstants constructor

PrefsConstants class

1. Constructors
2. PrefsConstants
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Constants
12. PREFS_KEY_CURRENT_FARM
13. PREFS_KEY_FARM
14. PREFS_KEY_HEALTH_DOUBT_NOTIFICATION
15. PREFS_KEY_NEED_CHECK_NOTIFICATION
16. PREFS_KEY_ODD_ACTION_NOTIFICATION
17. PREFS_KEY_QNA_NOTIFICATION
18. PREFS_KEY_VERSION