code: public AuthenticationResult authenticateRequest(WebRequest webRequest) {
          WebAuthenticator authenticator = getWebAuthenticatorProxy();
          return authenticator.authenticate(webRequest);
      }
docs: The main method called by the preInvoke. The return value of this method tells
  us if access to the requested resource is allowed or not.
  Delegates to the authenticator proxy to handle the authentication.
  
  @param webRequest
  @return AuthenticationResult