diff --git a/core/lib/Drupal/Core/Asset/AssetGroupSetHashTrait.php b/core/lib/Drupal/Core/Asset/AssetGroupSetHashTrait.php
index 3666605..9039726 100644
--- a/core/lib/Drupal/Core/Asset/AssetGroupSetHashTrait.php
+++ b/core/lib/Drupal/Core/Asset/AssetGroupSetHashTrait.php
@@ -25,4 +25,5 @@ protected function generateHash(array $groups) {
     }
     return hash('sha256', serialize($normalized));
   }
+
 }
diff --git a/core/lib/Drupal/Core/Asset/CssCollectionOptimizerLazy.php b/core/lib/Drupal/Core/Asset/CssCollectionOptimizerLazy.php
index 19ac573..46c3dac 100644
--- a/core/lib/Drupal/Core/Asset/CssCollectionOptimizerLazy.php
+++ b/core/lib/Drupal/Core/Asset/CssCollectionOptimizerLazy.php
@@ -139,5 +139,4 @@ public function optimize(array $css_assets) {
     return $css_assets;
   }
 
-
 }
diff --git a/core/lib/Drupal/Core/Asset/CssCollectionOptimizerTrait.php b/core/lib/Drupal/Core/Asset/CssCollectionOptimizerTrait.php
index e884003..f4057dc 100644
--- a/core/lib/Drupal/Core/Asset/CssCollectionOptimizerTrait.php
+++ b/core/lib/Drupal/Core/Asset/CssCollectionOptimizerTrait.php
@@ -66,8 +66,8 @@ public function deleteAll() {
    * @return string[]
    *   URIs for all optimized asset collection assets.
    */
- public function getAll() {
-   return $this->state->get('drupal_css_cache_files', []);
- }
+  public function getAll() {
+    return $this->state->get('drupal_css_cache_files', []);
+  }
 
 }
diff --git a/core/lib/Drupal/Core/Asset/JsCollectionOptimizerLazy.php b/core/lib/Drupal/Core/Asset/JsCollectionOptimizerLazy.php
index 1082970..58cc573 100644
--- a/core/lib/Drupal/Core/Asset/JsCollectionOptimizerLazy.php
+++ b/core/lib/Drupal/Core/Asset/JsCollectionOptimizerLazy.php
@@ -117,6 +117,7 @@ public function optimize(array $js_assets) {
           $uri = $js_group['items'][0]['data'];
           $js_assets[$order]['data'] = $uri;
           break;
+
         case 'setting':
           $js_assets[$order]['data'] = $js_group['data'];
           break;
@@ -124,7 +125,7 @@ public function optimize(array $js_assets) {
     }
     if ($libraries) {
       // Generate a URL for the group, but do not process it inline, this is
-      // done by \Drupal\system\controller\JsAssetController
+      // done by \Drupal\system\controller\JsAssetController.
       $ajax_page_state = $this->requestStack->getCurrentRequest()->query->get('ajax_page_state');
       $already_loaded = isset($ajax_page_state) ? explode(',', $ajax_page_state['libraries']) : [];
 
@@ -133,13 +134,13 @@ public function optimize(array $js_assets) {
         'theme' => $this->themeManager->getActiveTheme()->getName(),
         'already_loaded' => $this->dependencyResolver->getMinimalRepresentativeSubset($already_loaded),
       ];
-      $header_query = UrlHelper::buildQuery($query_args + ['scope'  => 'header']);
-      $footer_query = UrlHelper::buildQuery($query_args + ['scope'  => 'footer']);
+      $header_query = UrlHelper::buildQuery($query_args + ['scope' => 'header']);
+      $footer_query = UrlHelper::buildQuery($query_args + ['scope' => 'footer']);
       foreach ($js_assets as $order => $js_asset) {
         if (!empty($js_asset['preprocessed'])) {
           $query = $js_asset['scope'] == 'header' ? $header_query : $footer_query;
-          $filename = 'js' . '_' . $order . '_' . $key . '.js';
-          $uri = 'public://js' . '/' . $filename;
+          $filename = 'js_' . $order . '_' . $key . '.js';
+          $uri = 'public://js/' . $filename;
           $js_assets[$order]['data'] = file_create_url($uri) . '?' . $query;
         }
       }
diff --git a/core/lib/Drupal/Core/Asset/JsCollectionOptimizerTrait.php b/core/lib/Drupal/Core/Asset/JsCollectionOptimizerTrait.php
index 9bea1a8..4cbe72a 100644
--- a/core/lib/Drupal/Core/Asset/JsCollectionOptimizerTrait.php
+++ b/core/lib/Drupal/Core/Asset/JsCollectionOptimizerTrait.php
@@ -2,8 +2,6 @@
 
 namespace Drupal\Core\Asset;
 
-use Drupal\Core\State\StateInterface;
-
 /**
  * Optimizes JavaScript assets.
  */
@@ -74,5 +72,4 @@ public function getAll() {
     return $this->state->get('system.js_cache_files', []);
   }
 
-
 }
diff --git a/core/modules/system/src/Controller/AssetControllerBase.php b/core/modules/system/src/Controller/AssetControllerBase.php
index d56c59e..a763dcf 100644
--- a/core/modules/system/src/Controller/AssetControllerBase.php
+++ b/core/modules/system/src/Controller/AssetControllerBase.php
@@ -2,7 +2,6 @@
 
 namespace Drupal\system\Controller;
 
-use Drupal\Component\Utility\Crypt;
 use Drupal\Core\Asset\AssetCollectionGrouperInterface;
 use Drupal\Core\Asset\AssetCollectionOptimizerInterface;
 use Drupal\Core\Asset\AssetDumperUriInterface;
@@ -43,14 +42,14 @@
   /**
    * The theme initialization.
    *
-   * @var Drupal\Core\Theme\ThemeInitializationInterface;
+   * @var Drupal\Core\Theme\ThemeInitializationInterface
    */
   protected $themeInitialization;
 
   /**
    * The theme manager.
    *
-   * @var Drupal\Core\Theme\ThemeManagerInterface;
+   * @var Drupal\Core\Theme\ThemeManagerInterface
    */
   protected $themeManager;
 
@@ -105,27 +104,29 @@
 
   /**
    * The cache control header to use.
+   *
+   * @var string
    */
   protected $cacheControl = 'private, no-store';
 
   /**
    * Constructs a CssAssetController object.
    *
-   * @param \Drupal\Core\Asset\LibraryDependencyResolverInterface
+   * @param \Drupal\Core\Asset\LibraryDependencyResolverInterface $library_dependency_resolver
    *   The library dependency resolver.
-   * @param \Drupal\Core\Asset\AssetResolverInterface
+   * @param \Drupal\Core\Asset\AssetResolverInterface $asset_resolver
    *   The asset resolver.
-   * @param \Drupal\Core\Theme\ThemeInitializationInterface
+   * @param \Drupal\Core\Theme\ThemeInitializationInterface $theme_initialization
    *   The theme initializer.
-   * @param \Drupal\Core\Theme\ThemeManagerInterface
+   * @param \Drupal\Core\Theme\ThemeManagerInterface $theme_manager
    *   The theme manager.
-   * @param \Drupal\Core\Asset\AssetCollectionGrouperInterface
+   * @param \Drupal\Core\Asset\AssetCollectionGrouperInterface $grouper
    *   The asset grouper.
-   * @param \Drupal\Core\Asset\AssetCollectionOptimizerInterface
+   * @param \Drupal\Core\Asset\AssetCollectionOptimizerInterface $optimizer
    *   The asset collection optimizer.
-   * @param \Drupal\Core\Asset\AssetDumperUriInterface
+   * @param \Drupal\Core\Asset\AssetDumperUriInterface $dumper
    *   The asset dumper.
-   * @param \Drupal\Core\State\StateInterface
+   * @param \Drupal\Core\State\StateInterface $state
    *   The state service.
    */
   public function __construct(LibraryDependencyResolverInterface $library_dependency_resolver, AssetResolverInterface $asset_resolver, ThemeInitializationInterface $theme_initialization, ThemeManagerInterface $theme_manager, AssetCollectionGrouperInterface $grouper, AssetCollectionOptimizerInterface $optimizer, AssetDumperUriInterface $dumper, StateInterface $state) {
@@ -145,7 +146,7 @@ public function __construct(LibraryDependencyResolverInterface $library_dependen
    *
    * @param \Symfony\Component\HttpFoundation\Request $request
    *   The request object.
-   * @param $file_name
+   * @param string $file_name
    *   The file to deliver.
    *
    * @return \Symfony\Component\HttpFoundation\BinaryFileResponse|\Symfony\Component\HttpFoundation\Response
@@ -207,7 +208,7 @@ public function deliver(Request $request, $file_name) {
     // the same case as #1 but a much shorter window.
     // 3. Someone is attempting to craft an invalid URL in order to conduct a
     // denial of service attack on the site.
-
+    //
     // Dump the optimized group into an aggregate file, but only if the
     // received hash and generated hash match. This prevents invalid filenames
     // from filling the disk, while still serving aggregates that may be
@@ -235,11 +236,11 @@ public function deliver(Request $request, $file_name) {
    * Get a group.
    *
    * @param array $groups
-   *   An array of asset groups
-   *  @param int $group_delta
+   *   An array of asset groups.
+   * @param int $group_delta
    *    The group delta.
    *
-   * @return []
+   * @return array
    *   The correct asset group matching $group_delta.
    */
   protected function getGroup($groups, $group_delta) {
@@ -258,4 +259,5 @@ protected function getGroup($groups, $group_delta) {
    *   The current request.
    */
   abstract protected function getGroups(AttachedAssetsInterface $attached_assets, Request $request);
+
 }
diff --git a/core/tests/Drupal/FunctionalTests/Asset/AssetOptimizationTest.php b/core/tests/Drupal/FunctionalTests/Asset/AssetOptimizationTest.php
index ea26b9b..fee8b00 100644
--- a/core/tests/Drupal/FunctionalTests/Asset/AssetOptimizationTest.php
+++ b/core/tests/Drupal/FunctionalTests/Asset/AssetOptimizationTest.php
@@ -65,6 +65,14 @@ public function testAssetAggregation() {
     }
   }
 
+  /**
+   * Tests the URL points to a valid page, and has expected headers.
+   *
+   * @param string $url
+   *   The url under test.
+   * @param bool $from_php
+   *   (optional) is the source of the url php code. Default to TRUE.
+   */
   protected function assertAggregate($url, $from_php = TRUE) {
     $url = $this->getAbsoluteUrl($url);
     $session = $this->getSession();
@@ -79,6 +87,12 @@ protected function assertAggregate($url, $from_php = TRUE) {
     }
   }
 
+  /**
+   * Test the returned response code under various failure conditions.
+   *
+   * @param string $url
+   *   The url under tests.
+   */
   protected function assertInvalidAggregates($url) {
     $session = $this->getSession();
     $session->visit($this->replaceGroupDelta($url));
@@ -103,12 +117,30 @@ protected function assertInvalidAggregates($url) {
 
   }
 
+  /**
+   * Invalidate the group delta section of a URL.
+   *
+   * @param string $url
+   *   The URL to be modified.
+   *
+   * @return string
+   *   The modified absolute URL.
+   */
   protected function replaceGroupDelta($url) {
     $parts = explode('_', $url);
     $parts[1] = 100;
     return $this->getAbsoluteUrl(implode('_', $parts));
   }
 
+  /**
+   * Invalidate the hash section of the URL, for example to ensure a cache miss.
+   *
+   * @param string $url
+   *   The URL to be modified.
+   *
+   * @return string
+   *   The modified absolute URL.
+   */
   protected function replaceGroupHash($url) {
     $parts = explode('_', $url);
     $hash = strtok($parts[2], '.');
@@ -116,6 +148,15 @@ protected function replaceGroupHash($url) {
     return $this->getAbsoluteUrl(implode('_', $parts));
   }
 
+  /**
+   * Invalidate the library definition associated with a URL.
+   *
+   * @param string $url
+   *   The associated URL.
+   *
+   * @return string
+   *   The modified absolute URL.
+   */
   protected function setInvalidLibrary($url) {
     // First replace the hash so we don't get served the actual file on disk.
     $url = $this->replaceGroupHash($url);
@@ -126,14 +167,22 @@ protected function setInvalidLibrary($url) {
     return $this->getAbsoluteUrl($parts['path'] . '?' . $query . '#' . $parts['fragment']);
   }
 
+  /**
+   * Delete the theme section from a given URL.
+   *
+   * @param string $url
+   *   The URL to modify.
+   *
+   * @return string
+   *   The modified absolute URL.
+   */
   protected function omitTheme($url) {
     // First replace the hash so we don't get served the actual file on disk.
     $url = $this->replaceGroupHash($url);
     $parts = UrlHelper::parse($url);
     unset($parts['query']['theme']);
     $query = UrlHelper::buildQuery($parts['query']);
-    return $this->getAbsoluteUrl($parts['path'] . '?' .  $query . '#' .  $parts['fragment']);
+    return $this->getAbsoluteUrl($parts['path'] . '?' . $query . '#' . $parts['fragment']);
   }
 
-
 }