number property Null safety

1. baguette
2. CheckoutPhone
3. CheckoutPhone
4. number property

CheckoutPhone class

1. Constructors
2. CheckoutPhone
3. fromJson
4. Properties
5. countryCode
6. hashCode
7. number
8. runtimeType
9. Methods
10. noSuchMethod
11. toJson
12. toString
13. Operators
14. operator ==