diff --git a/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php b/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php
index 542cd0343c..27112213f8 100644
--- a/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php
+++ b/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php
@@ -13,7 +13,6 @@ namespace Symfony\Component\Cache\Tests\Adapter;
 
 use Cache\IntegrationTests\CachePoolTest;
 use PHPUnit\Framework\Assert;
-use PHPUnit\Framework\Warning;
 use Psr\Cache\CacheItemInterface;
 use Psr\Cache\CacheItemPoolInterface;
 use Symfony\Component\Cache\CacheItem;
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Compiler/ResolveBindingsPassTest.php b/src/Symfony/Component/DependencyInjection/Tests/Compiler/ResolveBindingsPassTest.php
index aa470f1e25..071d7f8818 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Compiler/ResolveBindingsPassTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Compiler/ResolveBindingsPassTest.php
@@ -12,7 +12,6 @@
 namespace Symfony\Component\DependencyInjection\Tests\Compiler;
 
 use PHPUnit\Framework\TestCase;
-use PHPUnit\Framework\Warning;
 use Symfony\Component\DependencyInjection\Argument\BoundArgument;
 use Symfony\Component\DependencyInjection\Compiler\AutowireRequiredMethodsPass;
 use Symfony\Component\DependencyInjection\Compiler\ResolveBindingsPass;
diff --git a/src/Symfony/Component/Form/Extension/DataCollector/FormDataCollectorInterface.php b/src/Symfony/Component/Form/Extension/DataCollector/FormDataCollectorInterface.php
index d2a7818cd0..64b8f83c4b 100644
--- a/src/Symfony/Component/Form/Extension/DataCollector/FormDataCollectorInterface.php
+++ b/src/Symfony/Component/Form/Extension/DataCollector/FormDataCollectorInterface.php
@@ -14,6 +14,7 @@ namespace Symfony\Component\Form\Extension\DataCollector;
 use Symfony\Component\Form\FormInterface;
 use Symfony\Component\Form\FormView;
 use Symfony\Component\HttpKernel\DataCollector\DataCollectorInterface;
+use Symfony\Component\VarDumper\Cloner\Data;
 
 /**
  * Collects and structures information about forms.
@@ -78,7 +79,7 @@ interface FormDataCollectorInterface extends DataCollectorInterface
     /**
      * Returns all collected data.
      *
-     * @return array
+     * @return array|Data
      */
     public function getData();
 }
diff --git a/src/Symfony/Component/HttpKernel/DataCollector/DataCollector.php b/src/Symfony/Component/HttpKernel/DataCollector/DataCollector.php
index d3020a312e..52ab90c669 100644
--- a/src/Symfony/Component/HttpKernel/DataCollector/DataCollector.php
+++ b/src/Symfony/Component/HttpKernel/DataCollector/DataCollector.php
@@ -28,6 +28,9 @@ use Symfony\Component\VarDumper\Cloner\VarCloner;
  */
 abstract class DataCollector implements DataCollectorInterface
 {
+    /**
+     * @var array|Data
+     */
     protected $data = [];
 
     /**