added the possibility to return null from SimplePreAuthenticationList…

…ener

src/Symfony/Component/Security/Http/Firewall/SimplePreAuthenticationListener.php

@@ -21,6 +21,7 @@
 use Symfony\Component\Security\Core\Exception\AuthenticationException;
 use Symfony\Component\Security\Http\Authentication\AuthenticationFailureHandlerInterface;
 use Symfony\Component\Security\Http\Authentication\AuthenticationSuccessHandlerInterface;
+use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;
 
 /**
  * SimplePreAuthenticationListener implements simple proxying to an authenticator.
@@ -75,9 +76,13 @@ public function handle(GetResponseEvent $event)
         }
 
         try {
+            $this->securityContext->setToken(null);
             $token = $this->simpleAuthenticator->createToken($request, $this->providerKey);
-            $token = $this->authenticationManager->authenticate($token);
-            $this->securityContext->setToken($token);
+
+            if ($token instanceof TokenInterface) {
+                $token = $this->authenticationManager->authenticate($token);
+                $this->securityContext->setToken($token);
+            }
         } catch (AuthenticationException $e) {
             $this->securityContext->setToken(null);