ProtectedBranch API create could return user/group ids on authorization failure
What
The protrected branches create API allows users/groups to be given access to a branch. When a user isn't a member of a project, or a group hasn't been invited to the project the request will fail. At the moment the error message isn't specific, but could instead list the users/groups which failed the validation.
Why
To make it simpler to correct the failed authorization, either by granting permission or removing the offending user/group from the request.