text property Null safety

1. netease_roomkit
2. netease_roomkit
3. NERoomChatTextMessage
4. text property

NERoomChatTextMessage class

1. Constructors
2. NERoomChatTextMessage
3. Properties
4. fromNick
5. fromUserUuid
6. hashCode
7. message
8. messageType
9. messageUuid
10. of
11. runtimeType
12. text
13. time
14. toUserUuidList
15. Methods
16. noSuchMethod
17. toString
18. Operators
19. operator *
20. operator ==