When we generate a JWT for the application, we extract Hopsworks username out of application user/project-specific user. This username is later used as the subject for the application's JWT. If application submitter is not in the form of ALPHANUMERIC__ALPHANUMERIC then an exception is thrown.
There are cases though, such as when using Slider, that the application submitter is just ALPHANUMERIC (ex 'hive'). If we can't extract the "real" username out of the project-specific username, then we should fallback to whatever is available.
WARNING: In that case, some endpoints in Hopsworks, which use JWT's subject for lookup will not be available.