NERoomChatController constructor Null safety

1. yunxin_roomkit
2. roomkit
3. NERoomChatController
4. NERoomChatController constructor

NERoomChatController class

1. Constructors
2. NERoomChatController
3. Properties
4. hashCode
5. isSupported
6. runtimeType
7. Methods
8. addAttachment
9. clearAttachments
10. getAttachment
11. joinChatroom
12. leaveChatroom
13. noSuchMethod
14. removeAttachment
15. sendBroadcastTextMessage
16. sendDirectTextMessage
17. sendGroupTextMessage
18. toString
19. Operators
20. operator ==