Use case
Return the display name of the previous assignee.
Expression
Create and configure a Smart field using this expression in Jira expression parsing mode:
let assignees= issue.changelogs.map(i=>i.items).flatten().filter(i=>i.field=="assignee");
assignees.length>0 ?
assignees.map(a=>a.fromString)[0] == null ?
""
:assignees.map(a=>a.fromString)[0]
: ""
