Versions are stored in lists. Documentation on how to work with lists can be found here.
You can access the whole version by issue?.versions[0] and issue?.fixVersions[0] which returns a Version object, issue?.versions will return a list of objects.
Read
Page properties
id
1
Returned value
Trueif the first (fix)version has been archived, false otherwise. If no (fix) version are available, null is returned.