diff --git a/core/modules/hal/src/Normalizer/CollectionNormalizer.php b/core/modules/hal/src/Normalizer/CollectionNormalizer.php
index c66cc64..025d9aa 100644
--- a/core/modules/hal/src/Normalizer/CollectionNormalizer.php
+++ b/core/modules/hal/src/Normalizer/CollectionNormalizer.php
@@ -1,10 +1,5 @@
 <?php
 
-/**
- * @file
- * Contains \Drupal\hal\Normalizer\CollectionNormalizer.
- */
-
 namespace Drupal\hal\Normalizer;
 
 use Drupal\rest\LinkManager\LinkManagerInterface;
@@ -43,6 +38,7 @@ public function __construct(LinkManagerInterface $link_manager) {
    * {@inheritdoc}
    */
   public function normalize($object, $format = NULL, array $context = []) {
+    /** @var $entity \Drupal\serialization\Collection */
     // Create the array of normalized properties, starting with the URI.
     $normalized = [
       '_links' => [
@@ -52,12 +48,6 @@ public function normalize($object, $format = NULL, array $context = []) {
       ],
     ];
 
-    // $object is not type-hinted, so we cannot be sure this method will not be
-    // called on a non-Collection object, and there is no interface to check on.
-    if (!$object instanceof Collection) {
-      return $normalized;
-    }
-
     // If we have additional hypermedia links add them here.
     $links = $object->getLinks();
     if (is_array($links) && count($links)) {
diff --git a/core/modules/hal/tests/src/Unit/CollectionNormalizerTest.php b/core/modules/hal/tests/src/Unit/CollectionNormalizerTest.php
index 7953815..30c6031 100644
--- a/core/modules/hal/tests/src/Unit/CollectionNormalizerTest.php
+++ b/core/modules/hal/tests/src/Unit/CollectionNormalizerTest.php
@@ -1,8 +1,4 @@
 <?php
-/**
- * @file
- * Contains \Drupal\hal\Tests\CollectionNormalizerTest.
- */
 
 namespace Drupal\Tests\hal\Unit;
 
diff --git a/core/modules/rest/src/LinkManager/CollectionLinkManager.php b/core/modules/rest/src/LinkManager/CollectionLinkManager.php
index 2175a0c..f6acdac 100644
--- a/core/modules/rest/src/LinkManager/CollectionLinkManager.php
+++ b/core/modules/rest/src/LinkManager/CollectionLinkManager.php
@@ -1,10 +1,5 @@
 <?php
 
-/**
- * @file
- * Contains \Drupal\rest\LinkManager\CollectionLinkManager.
- */
-
 namespace Drupal\rest\LinkManager;
 
 /**
diff --git a/core/modules/rest/src/LinkManager/CollectionLinkManagerInterface.php b/core/modules/rest/src/LinkManager/CollectionLinkManagerInterface.php
index e51924c..a1c3b7e 100644
--- a/core/modules/rest/src/LinkManager/CollectionLinkManagerInterface.php
+++ b/core/modules/rest/src/LinkManager/CollectionLinkManagerInterface.php
@@ -1,10 +1,5 @@
 <?php
 
-/**
- * @file
- * Contains \Drupal\rest\LinkManager\CollectionLinkManagerInterface.
- */
-
 namespace Drupal\rest\LinkManager;
 
 /**
diff --git a/core/modules/serialization/src/Collection.php b/core/modules/serialization/src/Collection.php
index c6f7301..6022c50 100644
--- a/core/modules/serialization/src/Collection.php
+++ b/core/modules/serialization/src/Collection.php
@@ -1,10 +1,5 @@
 <?php
 
-/**
- * @file
- * Contains \Drupal\serialization\Collection
- */
-
 namespace Drupal\serialization;
 
 /**
diff --git a/core/modules/serialization/tests/src/Unit/CollectionTest.php b/core/modules/serialization/tests/src/Unit/CollectionTest.php
index eadbce8..978e995 100644
--- a/core/modules/serialization/tests/src/Unit/CollectionTest.php
+++ b/core/modules/serialization/tests/src/Unit/CollectionTest.php
@@ -1,10 +1,5 @@
 <?php
 
-/**
- * @file
- * Contains \Drupal\serialization\Tests\CollectionTest.
- */
-
 namespace Drupal\Tests\serialization\Unit;
 
 use Drupal\serialization\Collection;