ReplyType constructor Null safety

1. sendbird_sdk
2. enums
3. ReplyType
4. ReplyType const constructor

ReplyType enum

1. Constructors
2. ReplyType
3. Values
4. none
5. all
6. only_reply_to_channel
7. Properties
8. hashCode
9. index
10. runtimeType
11. Methods
12. noSuchMethod
13. toString
14. Operators
15. operator ==
16. Constants
17. values