Merge branch '4.1' into 4.2

* 4.1:
  Fix typos in doc blocks
  [Debug] ignore underscore vs backslash namespaces in DebugClassLoader
  [TwigBridge][Form] Prevent multiple rendering of form collection prototypes
  [FrameworkBundle] fix describing routes with no controllers
  [DI] move RegisterServiceSubscribersPass before DecoratorServicePass
  Update ValidationListener.php
  [Yaml] ensures that the mb_internal_encoding is reset to its initial value
  [WebLink] Fixed documentation link
  [Security] getTargetPath of TargetPathTrait must return string or null
  [Hackday][Serializer] Deserialization ignores argument type hint from phpdoc for array in constructor argument
  Optimize perf by replacing call_user_func with dynamic vars
  [Routing] fix dumping same-path routes with placeholders
  [Security] defer log message in guard authenticator
  [Validator] Added IBAN format for Vatican City State
  merge conflicts
  filter out invalid Intl values
  filter out invalid language values
  [Validator] Fixed grouped composite constraints
  [Form] Filter arrays out of scalar form types
  Fix HeaderBag::get phpdoc

Author: nicolas-grekas

Guard/Firewall/GuardAuthenticationListener.php

@@ -96,14 +96,22 @@ private function executeGuardAuthenticator($uniqueGuardKey, AuthenticatorInterfa
         $request = $event->getRequest();
         try {
             if (null !== $this->logger) {
-                $this->logger->debug('Calling getCredentials() on guard authenticator.', array('firewall_key' => $this->providerKey, 'authenticator' => \get_class($guardAuthenticator)));
+                $this->logger->debug('Checking support on guard authenticator.', array('firewall_key' => $this->providerKey, 'authenticator' => \get_class($guardAuthenticator)));
             }
 
             // abort the execution of the authenticator if it doesn't support the request
             if (!$guardAuthenticator->supports($request)) {
+                if (null !== $this->logger) {
+                    $this->logger->debug('Guard authenticator does not support the request.', array('firewall_key' => $this->providerKey, 'authenticator' => \get_class($guardAuthenticator)));
+                }
+
                 return;
             }
 
+            if (null !== $this->logger) {
+                $this->logger->debug('Calling getCredentials() on guard authenticator.', array('firewall_key' => $this->providerKey, 'authenticator' => \get_class($guardAuthenticator)));
+            }
+
             // allow the authenticator to fetch authentication info from the request
             $credentials = $guardAuthenticator->getCredentials($request);
 

Http/Util/TargetPathTrait.php

@@ -38,7 +38,7 @@ private function saveTargetPath(SessionInterface $session, $providerKey, $uri)
      * @param SessionInterface $session
      * @param string           $providerKey The name of your firewall
      *
-     * @return string
+     * @return string|null
      */
     private function getTargetPath(SessionInterface $session, $providerKey)
     {