comment property Null safety

1. Flutter
2. archive_io
3. ArchiveFile
4. comment property

ArchiveFile class

1. Constructors
2. ArchiveFile
3. noCompress
4. stream
5. string
6. Properties
7. comment
8. compress
9. compressionType
10. content
11. crc32
12. groupId
13. hashCode
14. isCompressed
15. isFile
16. isSymbolicLink
17. lastModTime
18. mode
19. name
20. nameOfLinkedFile
21. ownerId
22. rawContent
23. runtimeType
24. size
25. unixPermissions
26. Methods
27. clear
28. close
29. decompress
30. noSuchMethod
31. toString
32. writeContent
33. Operators
34. operator ==
35. Constants
36. DEFLATE
37. STORE