NumericConstants constructor Null safety

1. farmershands
2. numeric_constants
3. NumericConstants
4. NumericConstants constructor

NumericConstants class

1. Constructors
2. NumericConstants
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Static properties
12. activityScale