Jenkins: List of authenticated users

def isAuthenticated(User u) {
  try {
    return u.impersonate().isAuthenticated()
  }
  // Users pulled from SCM history e.a. are not GUI users
  catch (org.acegisecurity.userdetails.UsernameNotFoundException xc) {
    return false
  }
}

User.getAll().findAll { isAuthenticated(it) }