diff --git a/core/lib/Drupal/Core/Asset/AssetDumper.php b/core/lib/Drupal/Core/Asset/AssetDumper.php
index 533f602..7c3afdd 100644
--- a/core/lib/Drupal/Core/Asset/AssetDumper.php
+++ b/core/lib/Drupal/Core/Asset/AssetDumper.php
@@ -7,7 +7,7 @@
 /**
  * Dumps a CSS or JavaScript asset.
  */
-class AssetDumper implements AssetDumperInterface {
+class AssetDumper implements AssetDumperUriInterface {
 
   /**
    * {@inheritdoc}
@@ -16,15 +16,20 @@ class AssetDumper implements AssetDumperInterface {
    * the aggregated contents of the files in $data. This forces proxies and
    * browsers to download new CSS when the CSS changes.
    */
-  public function dump($data, $file_extension, $uri = NULL) {
-    // Create the css/ or js/ path within the files folder.
+  public function dump($data, $file_extension) {
+    $path = 'public://' . $file_extension;
+    // Prefix filename to prevent blocking by firewalls which reject files
+    // starting with "ad*".
+    $filename = $file_extension . '_' . Crypt::hashBase64($data) . '.' . $file_extension;
+    $uri = $path . '/' . $filename;
+    return $this->dumpToUri($data, $file_extension, $uri);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function dumpToUri($data, $file_extension, $uri) {
     $path = 'public://' . $file_extension;
-    if (!isset($uri)) {
-      // Prefix filename to prevent blocking by firewalls which reject files
-      // starting with "ad*".
-      $filename = $file_extension . '_' . Crypt::hashBase64($data) . '.' . $file_extension;
-      $uri = $path . '/' . $filename;
-    }
     // Create the CSS or JS file.
     file_prepare_directory($path, FILE_CREATE_DIRECTORY);
     if (!file_exists($uri) && !file_unmanaged_save_data($data, $uri, FILE_EXISTS_REPLACE)) {
diff --git a/core/lib/Drupal/Core/Asset/AssetDumperInterface.php b/core/lib/Drupal/Core/Asset/AssetDumperInterface.php
index e7d0ac9..2b53eb1 100644
--- a/core/lib/Drupal/Core/Asset/AssetDumperInterface.php
+++ b/core/lib/Drupal/Core/Asset/AssetDumperInterface.php
@@ -15,12 +15,9 @@
    * @param string $file_extension
    *   The file extension of this asset.
    *
-   * @param string $uri
-   *   (optional) The file URI to write to.
-   *
    * @return string
    *   An URI to access the dumped asset.
    */
-  public function dump($data, $file_extension, $uri = NULL);
+  public function dump($data, $file_extension);
 
 }
diff --git a/core/modules/system/src/Controller/AssetControllerBase.php b/core/modules/system/src/Controller/AssetControllerBase.php
index b2a32fa..03f44da 100644
--- a/core/modules/system/src/Controller/AssetControllerBase.php
+++ b/core/modules/system/src/Controller/AssetControllerBase.php
@@ -65,7 +65,7 @@
   /**
    * An asset dumper.
    *
-   * @var \Drupal\Core\Asset\AssetDumperInterface
+   * @var \Drupal\Core\Asset\AssetDumperUriInterface
    */
   protected $dumper;
 
@@ -110,10 +110,10 @@
    *   The asset grouper.
    * @param \Drupal\Core\Asset\AssetOptimizerInterface
    *   The optimizer for a single asset.
-   * @param \Drupal\Core\Asset\AssetDumperInterface
+   * @param \Drupal\Core\Asset\AssetDumperUriInterface
    *   The asset dumper.
    */
-  public function __construct($library_dependency_resolver, $asset_resolver, $theme_initialization, $theme_manager, $grouper, $optimizer, $dumper) {
+  public function __construct(LibraryDependencyResolverInterface $library_dependency_resolver, AssetResolverInterface $asset_resolver, ThemeInitializationInterface $theme_initialization, ThemeManagerInterface $theme_manager, AssetCollectionGrouperInterface $grouper, AssetOptimizerInterface $optimizer, AssetDumperUriInterface $dumper) {
     $this->libraryDependencyResolver = $library_dependency_resolver;
     $this->assetResolver = $asset_resolver;
     $this->themeInitialization = $theme_initialization;
@@ -162,9 +162,8 @@ public function deliver(Request $request, $file_name) {
     if ($request->query->has('already_loaded')) {
       $attached_assets->setAlreadyLoadedLibraries($request->query->get('already_loaded'));
     }
-    $key_and_group = $this->getKeyAndGroup($attached_assets, $group_delta, $request);
-    $key = $key_and_group['key'];
-    $group = $key_and_group['group'];
+    $group = $this->getGroup($attached_assets, $group_delta, $request);
+    $key = $this->generateHash($group);
     $hash = $file_parts[2];
 
     // The hash from the library definitions in code may not match the hash from
diff --git a/core/modules/system/src/Controller/CssAssetController.php b/core/modules/system/src/Controller/CssAssetController.php
index 8f1b0b5..112dbfb 100644
--- a/core/modules/system/src/Controller/CssAssetController.php
+++ b/core/modules/system/src/Controller/CssAssetController.php
@@ -49,12 +49,7 @@ protected function getKeyAndGroup(AttachedAssetsInterface $attached_assets, $gro
     if (!isset($groups[$group_delta])) {
       throw new BadRequestHttpException('Invalid filename.');
     }
-    $group = $groups[$group_delta];
-    $key = $this->generateHash($groups);
-    return [
-      'group' => $group,
-      'key' => $key,
-    ];
+    return $groups[$group_delta];
   }
 
   /**
diff --git a/core/modules/system/src/Controller/JsAssetController.php b/core/modules/system/src/Controller/JsAssetController.php
index 4fdf401..6a92a85 100644
--- a/core/modules/system/src/Controller/JsAssetController.php
+++ b/core/modules/system/src/Controller/JsAssetController.php
@@ -42,7 +42,7 @@ public static function create(ContainerInterface $container) {
   /**
    * {@inheritdoc}
    */
-  protected function getKeyAndGroup(AttachedAssetsInterface $attached_assets, $group_delta, $request) {
+  protected function getGroup(AttachedAssetsInterface $attached_assets, $group_delta, $request) {
     // The header and footer scripts are two distinct sets of asset groups. The
     // $group_key is not sufficient to find the group, we also need to locate it
     // within either the header or footer set.
@@ -61,11 +61,7 @@ protected function getKeyAndGroup(AttachedAssetsInterface $attached_assets, $gro
       throw new BadRequestHttpException('Invalid filename.');
     }
     $group = $groups[$group_delta];
-    $key = $this->generateHash($groups);
-    return [
-      'group' => $group,
-      'key' => $key,
-    ];
+    return $group;
   }
 
   /**