EnumUtils constructor Null safety

1. tencent_im_sdk_plugin
2. utils
3. EnumUtils
4. EnumUtils constructor

EnumUtils class

1. Constructors
2. EnumUtils
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Static methods
12. convertFriendApplicationTypeEnum
13. convertFriendResponseTypeEnum
14. convertFriendTypeEnum
15. convertGroupMemberFilterEnum
16. convertGroupMemberRoleTypeEnum
17. convertHistoryMsgGetTypeEnum
18. convertLogLevelEnum
19. convertMessagePriorityEnum
20. convertReceiveMsgOptEnum