HttpRule_Pattern constructor Null safety

1. spine_client
2. http.pb
3. HttpRule_Pattern
4. HttpRule_Pattern const constructor

HttpRule_Pattern enum

1. Constructors
2. HttpRule_Pattern
3. Values
4. get
5. put
6. post
7. delete
8. patch
9. custom
10. notSet
11. Properties
12. hashCode
13. index
14. runtimeType
15. Methods
16. noSuchMethod
17. toString
18. Operators
19. operator ==
20. Constants
21. values