ChannelFileMessageUpdateApiRequest constructor Null safety

1. sendbird_sdk
2. file_message_update_request
3. ChannelFileMessageUpdateApiRequest
4. ChannelFileMessageUpdateApiRequest constructor

ChannelFileMessageUpdateApiRequest class

1. Constructors
2. ChannelFileMessageUpdateApiRequest
3. Properties
4. body
5. bypassAuth
6. hashCode
7. headers
8. isMultipart
9. method
10. progress
11. queryParams
12. runtimeType
13. state
14. token
15. url
16. userId
17. version
18. Methods
19. noSuchMethod
20. response
21. toString
22. Operators
23. operator ==