How to restrict Jira user to see only users of his group?

Question

I've encountered a situation, where Jira user that belongs to specific group, is able to see other users, that don't belong to his group, while assigning the issue. Can someone point me how to limit the user to see only users from his group? P.s this user has appropriate permissions only to this space and he's not admin user.

Nic Brough -Adaptavist- · Accepted Answer

There is no way to do this.  The "assignee" list is controlled by the perission scheme, and that holds rules such as "member of a named group, member of a role, reporter, named in a field" and so on.  There is no rule for "member of one of the same groups as the current user", because that could make the list nonsense for different users, and you'll find in almost all JIRA installs, everyone IS in the same group as everyone else - the "can log in" group.