Merge branch '4.4'

* 4.4:
  [Debug] Improve UPGRADE files
  remove wrongly added legacy group from test
  consistently throw NotSupportException
  [HttpKernel] Clarify error handler restoring process again
  [HttpClient] Remove CURLOPT_CONNECTTIMEOUT_MS curl opt
  add missing conflict rule
  [Intl] fix nullable phpdocs and useless method visibility of internal class
  remove some more useless phpdocs
  Resilience against file_get_contents() race conditions.
  Turned return type annotations of private methods into php return types.

Loader/XmlFileLoader.php

@@ -253,11 +253,9 @@ protected function loadFile($file)
     /**
      * Parses the config elements (default, requirement, option).
      *
-     * @return array An array with the defaults as first item, requirements as second and options as third
-     *
      * @throws \InvalidArgumentException When the XML is invalid
      */
-    private function parseConfigs(\DOMElement $node, string $path)
+    private function parseConfigs(\DOMElement $node, string $path): array
     {
         $defaults = [];
         $requirements = [];

Router.php

@@ -362,10 +362,8 @@ protected function getMatcherDumperInstance()
     /**
      * Provides the ConfigCache factory implementation, falling back to a
      * default implementation if necessary.
-     *
-     * @return ConfigCacheFactoryInterface
      */
-    private function getConfigCacheFactory()
+    private function getConfigCacheFactory(): ConfigCacheFactoryInterface
     {
         if (null === $this->configCacheFactory) {
             $this->configCacheFactory = new ConfigCacheFactory($this->options['debug']);