Merge branch '4.4' into 5.0

* 4.4: (30 commits)
  [Security] Check UserInterface::getPassword is not null before calling needsRehash
  gracefully handle missing event dispatchers
  Fix TokenStorage::reset not called in stateless firewall
  [DotEnv] Remove `usePutEnv` property default value
  [HttpFoundation] get currently session.gc_maxlifetime if ttl doesnt exists
  Set up typo fix
  [DependencyInjection] Handle env var placeholders in CheckTypeDeclarationsPass
  [Cache] fix memory leak when using PhpArrayAdapter
  [Validator] Allow underscore character "_" in URL username and password
  [TwigBridge] Update bootstrap_4_layout.html.twig
  [FrameworkBundle][SodiumVault] Create secrets directory only when needed
  fix parsing negative octal numbers
  [SecurityBundle] Passwords are not encoded when algorithm set to \"true\"
  [DependencyInjection] Resolve expressions in CheckTypeDeclarationsPass
  [SecurityBundle] Properly escape regex in AddSessionDomainConstraintPass
  do not validate passwords when the hash is null
  [DI] fix resolving bindings for named TypedReference
  [Config] never try loading failed classes twice with ClassExistenceResource
  [Mailer] Fix SMTP Authentication when using STARTTLS
  [DI] Fix making the container path-independent when the app is in /app
  ...

Author: nicolas-grekas

Firewall/ContextListener.php

@@ -66,7 +66,13 @@ public function __construct(TokenStorageInterface $tokenStorage, iterable $userP
         $this->userProviders = $userProviders;
         $this->sessionKey = '_security_'.$contextKey;
         $this->logger = $logger;
-        $this->dispatcher = LegacyEventDispatcherProxy::decorate($dispatcher);
+
+        if (null !== $dispatcher && class_exists(LegacyEventDispatcherProxy::class)) {
+            $this->dispatcher = LegacyEventDispatcherProxy::decorate($dispatcher);
+        } else {
+            $this->dispatcher = $dispatcher;
+        }
+
         $this->trustResolver = $trustResolver ?: new AuthenticationTrustResolver(AnonymousToken::class, RememberMeToken::class);
         $this->sessionTrackerEnabler = $sessionTrackerEnabler;
     }