User u = (User) userMgr.getAuthorizable(uID);
Impersonation impersonation = u.getImpersonation();
assertFalse(impersonation.grantImpersonation(adminPrincipal));
assertFalse(impersonation.revokeImpersonation(adminPrincipal));
assertTrue(impersonation.allows(buildSubject(adminPrincipal)));
// same if the impersonation object of the admin itself is used.
Impersonation adminImpersonation = ((User) a).getImpersonation();
assertFalse(adminImpersonation.grantImpersonation(adminPrincipal));