Merge branch '2.7' into 2.8

* 2.7:
  [Config] Handle nullable node name + fix inheritdocs
  [Security] added userChecker to SimpleAuthenticationProvider
  [Debug] fix test
  Fix typo in test method name
  Fixes #26563 (open_basedir restriction in effect)
  [Debug] Reset previous exception handler ealier to prevent infinite loop
  add hint in Github pull request template
  [Validator] Fix docblock of ClassMetadata#members
  [BrowserKit] Fix cookie path handling when $domain is null
  [DoctrineBridge] Don't rely on ClassMetadataInfo->hasField in DoctrineOrmTypeGuesser anymore
  [BrowserKit] Improves CookieJar::get
  [BrowserKit] Fix Cookie's PHPDoc
  [DomCrawler] Change bad wording in ChoiceFormField::untick
  [DomCrawler] Fix the PHPDoc of ChoiceFormField::setValue
  [DomCrawler] Avoid a useless call to strtolower
  [FrameworkBundle] HttpCache is not longer abstract
  [DomCrawler] extract(): fix a bug when the attribute list is empty
  [Config] Backport string|null api for node names

Author: nicolas-grekas

Mapping/ClassMetadata.php

@@ -48,7 +48,7 @@ class ClassMetadata extends ElementMetadata implements ClassMetadataInterface
     public $defaultGroup;
 
     /**
-     * @var MemberMetadata[]
+     * @var MemberMetadata[][]
      *
      * @internal This property is public in order to reduce the size of the
      *           class' serialized representation. Do not access it. Use