REST API: Change in behaviour of "Find users with browse permission" (GET /rest/user/viewissue/search)


after migrating from JIRA 8.13.20 to 8.20.9 (JIRA Server) we noticed an unexpected change in the GET /rest/user/viewissue/search endpoint [0].

In JIRA 8.13.20 we needed to pass "" for the parameter username to fetch all useres with view permissions. In JIRA 8.20.9 we need to leave the parameter username empty. Otherwise no users will be returned.

I scanned the release notes and search in JIRA’s JIRA but found no releated issue for this change.
Can sombody point me to a ticket or other documentation where this breaking change ist described? Or is this an unexpected change?

The API docs state a different expected behaviour:

username string the username filter, no users returned if left blank

What is the expected way to search for all users with browse permissions for an issue?

When the username parameter is omitted, the API responds with an error. But the error handling also changed:
In JIRA 8.13.20 the API responds 400 Bad Request, when the username is omitted, in JIRA 8.20.9 the error response is 500 Internal Server Error.

Many thanks in advance,