We have a basic rule in JIRA where active users that are assigned to or reported an issue can not be deleted as explained in this document. Again users or groups can not be renamed in JIRA and a feature request have since be tracked at JRA-1391 and JRA-1549 respectively.

If we integrate JIRA with a crowd server or LDAP directory and try to perform the operations above, an exception should be raised appropriately. In the present situation right now, no exception is raised and end up getting invalid users or groups.

Steps to replicate

1. create an application in crowd with some users as shown in screen-shot1
2. The users will be shown in JIRA after synchronization as shown in screen-shot2
3. Create an issue with the crowd directory users as the reporter of the issue and then try to delete the user. JIRA will raise a warning. See screen-shot3
4. Go to crowd and delete the user. No exception will be raised and user will be deleted. See screen-shot4
5. Synchronize directory in JIRA and user will still be inactive. See screen-shot5

This is more handful in the case where a group is renamed as a lot of schemes such as the permission scheme will be broken.