APIContact.empty constructor Null safety

1. conduit_open_api
2. open_api_v3
3. APIContact
4. APIContact.empty constructor

APIContact class

1. Constructors
2. APIContact
3. empty
4. Properties
5. castMap
6. email
7. extensions
8. hashCode
9. name
10. referenceURI
11. runtimeType
12. url
13. Methods
14. decode
15. encode
16. noSuchMethod
17. toString
18. Operators
19. operator ==