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

Session/Storage/Handler/SessionHandlerFactory.php

@@ -54,7 +54,7 @@ public static function createHandler($connection): AbstractSessionHandler
             case 0 === strpos($connection, 'rediss:'):
             case 0 === strpos($connection, 'memcached:'):
                 if (!class_exists(AbstractAdapter::class)) {
-                    throw new InvalidArgumentException(sprintf('Unsupported DSN "%s". Try running "composer require symfony/cache".', $connection));
+                    throw new \InvalidArgumentException(sprintf('Unsupported DSN "%s". Try running "composer require symfony/cache".', $connection));
                 }
                 $handlerClass = 0 === strpos($connection, 'memcached:') ? MemcachedSessionHandler::class : RedisSessionHandler::class;
                 $connection = AbstractAdapter::createConnection($connection, ['lazy' => true]);