opacity_zero constant Null safety

1. baguette
2. Values
3. Values
4. opacity_zero constant

Values class

1. Constructors
2. Values
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Constants
12. offset_year
13. opacity_full
14. opacity_half
15. opacity_zero