Merge branch '4.4'

* 4.4:
  cs fix
  Fix inconsistent return points.
  [Config] Add handling for ignored keys in ArrayNode::mergeValues.
  Fix inconsistent return points.
  [Security/Core] UserInterface::getPassword() can return null
  cs fix
  cs fix
  Fix missing exporter in PHPUnit constraint poylfill
  added `Process::getLastOutputTime()` method
  [Router] Fix TraceableUrlMatcher behaviour with trailing slash
  [HttpKernel] Remove outdated docblock comment
  Fix handling for session parameters
  Revert "bug #33092 [DependencyInjection] Improve an exception message (fabpot)"

Author: nicolas-grekas

User/UserInterface.php

@@ -52,7 +52,7 @@ public function getRoles();
      * This should be the encoded password. On authentication, a plain-text
      * password will be salted, encoded, and then compared to this value.
      *
-     * @return string The password
+     * @return string|null The encoded password if any
      */
     public function getPassword();