Username appears multiple times when in JQL filter if user is member of multiple directories

Issue Summary

Username appears multiple times when in JQL filter if user is member of multiple directories

Steps to Reproduce

1. Create the user in Jira Directory,
2. Create the same user in another Directory e.g. Active Directory,
3. Synchronize this Directory with Jira,
4. Now you can see multiple users in JQL,
5. Restarting Jira resolves the problem.

Expected Results

Username appears only once

Actual Results

Username appears several times, depending on how many directories is this user member of.

Workaround

1. Restart JIRA to clear the user cache.
2. Connect Jira to new empty directory, sync it and then remove it:
   1. Create new empty (dummy) directory
   2. Connect new Directory to Jira and synchronize this new Directory (after this step caches will revalidate and duplication should disappear)
   3. Remove this new empty Directory.