Provides context for the Attachments block on the View Issue page.
Return a key that is unique for the scope that this context should be scoped. E.g. If the context is unique per
issue, per user return "JRA-11234:nmenere"
||the context passed into the getContextMap method.
- a key that is unique for the scope that this context
- a Comparator<Attachment> according to the user's selection.