SmoothItModel constructor Null safety

1. smooth_app
2. smooth_it_model
3. SmoothItModel
4. SmoothItModel constructor

SmoothItModel class

1. Constructors
2. SmoothItModel
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. getMatchedProducts
8. noSuchMethod
9. refresh
10. toString
11. Operators
12. operator ==