@Test
public void obtainSubjectNullSubject() throws Exception {
LoginContext ctx = new LoginContext("obtainSubjectNullSubject", null, callbackHandler, testConfiguration);
assertNull(ctx.getSubject());
token = new JaasAuthenticationToken("un", "pwd", AuthorityUtils.createAuthorityList("ROLE_ADMIN"), ctx);
SecurityContextHolder.getContext().setAuthentication(token);
assertNullSubject(filter.obtainSubject(request));
}