Updating roles through REST API did not work using username

Summary:

In case that a user has been renamed before where app_user table will have the user_key and lower_user_name different, if we use the REST Call to include a user into a certain project role, it will fail.

Steps to reproduce:

1. Cerate a User that able to log in to JIRA.
2. Rename the User.
3. Execute the REST Call below:

   POST /rest/api/2/project/{projectIdOrKey}/role/{id}

4. For example,

   curl -X POST --data '{"user":["user1"]}' localhost:8730/jira/rest/api/2/project/BA/role/10002 -H 'Content-type: application/json' -H'Accept: application/json' -u admin:admin

Expected Result:

The user will be added to the role.

Actual Result:

This will be thrown instead:

{"errorMessages":["We can't find 'user1' in any accessible user directory. Check they're still active and available, and try again."],"errors":{}}

Workaround:

Use the user user_key. To check the value, run the query below:

select * from app_user where lower_user_name = '<affected username in lowercase>';

Notes:

• With JIRA Public REST API documentation did not specify which need to be used, the expected here is that the REST Call is possible to use the username
• In any case, JIRA should be able to check the lower_user_name in app_user table what is the original username is.