params.put(OAuthConsumerParameter.oauth_callback.toString(), "mycallback");
ConsumerAuthentication authentication = new ConsumerAuthentication(consumerDetails, creds, params);
authentication.setAuthenticated(true);
SecurityContextHolder.getContext().setAuthentication(authentication);
filter.onValidSignature(request, response, filterChain);
assertEquals("oauth_token=tokvalue&oauth_token_secret=shhhhhh&oauth_callback_confirmed=true", writer.toString());
SecurityContextHolder.getContext().setAuthentication(null);
}