PredominantBackground constructor Null safety

1. cloudinary_url_gen
2. predominant_background
3. PredominantBackground
4. PredominantBackground constructor

PredominantBackground class

1. Constructors
2. PredominantBackground
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. contrast
8. getValues
9. noSuchMethod
10. palette
11. toString
12. Operators
13. operator ==