Merge branch '4.4' into 5.0

* 4.4:
  Add missing use statements
  [Translation] Add missing use statement
  [Translation] Add missing use statement
  [Config][XmlReferenceDumper] Prevent potential \TypeError
  [Mailer] Fix broken mandrill http send for recipients with names
  [Translation] prefer intl domain when adding messages to catalogue
  Fix CS
  Fix CS
  Fail on empty password verification (without warning on any implementation)
  [Translation][Debug] Add installation and minimal example to README
  [Validator] try to call __get method if property is uninitialized
  Show both missing packages in the same error message
  Fix handling of empty_data's \Closure value in Date/Time form types

Author: fabpot

Firewall.php

@@ -15,6 +15,7 @@
 use Symfony\Component\HttpKernel\Event\FinishRequestEvent;
 use Symfony\Component\HttpKernel\Event\RequestEvent;
 use Symfony\Component\HttpKernel\KernelEvents;
+use Symfony\Component\Security\Http\Firewall\AbstractListener;
 use Symfony\Component\Security\Http\Firewall\AccessListener;
 use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;