As describe in this github issue https://github.com/jenkinsci/oic-auth-plugin/issues/343

Expected Results

During a Jenkins build, the BUILD_USER_GROUPS environment variable contains the groups of the user.

Actual Results

The variable is empty and a message is logged WARNING o.j.p.b.v.i.UserIdCauseDeterminant#setJenkinsUserBuildVars: Failed to get groups for user: myuser error: hudson.security.UserMayOrMayNotExistException2: Unable to query user information: myUser Show context

Analysis

[...]it throws UserMayOrMayNotExistException2 because at this point it does not, in fact, know for sure whether the user exists or not.

The fault lies in the build-user-vars-plugin for directly calling SecurityRealm.loadUserByUsername2 rather than going through User.getAuthorities, which is what would fall back to LastGrantedAuthoritiesProperty (via ImpersonatingUserDetailsService2).