Merge branch '2.8' into 3.4

* 2.8:
  Remove the Expires header when calling Response::expire()
  Allow multidimensional collection in property info

src/Symfony/Component/HttpFoundation/Response.php

@@ -718,6 +718,7 @@ class Response
     {
         if ($this->isFresh()) {
             $this->headers->set('Age', $this->getMaxAge());
+            $this->headers->remove('Expires');
         }
 
         return $this;

src/Symfony/Component/HttpFoundation/Tests/ResponseTest.php

@@ -362,6 +362,11 @@ class ResponseTest extends ResponseTestCase
         $response->headers->set('Expires', -1);
         $response->expire();
         $this->assertNull($response->headers->get('Age'), '->expire() does not set the Age when the response is expired');
+
+        $response = new Response();
+        $response->headers->set('Expires', date(DATE_RFC2822, time() + 600));
+        $response->expire();
+        $this->assertNull($response->headers->get('Expires'), '->expire() removes the Expires header when the response is fresh');
     }
 
     public function testGetTtl()

src/Symfony/Component/PropertyInfo/Tests/Fixtures/Dummy.php

@@ -46,6 +46,16 @@ class Dummy extends ParentDummy
      */
     public $collection;
 
+    /**
+     * @var string[][]
+     */
+    public $nestedCollection;
+
+    /**
+     * @var mixed[]
+     */
+    public $mixedCollection;
+
     /**
      * @var ParentDummy
      */