diff --git a/core/lib/Drupal/Core/Config/ConfigFactory.php b/core/lib/Drupal/Core/Config/ConfigFactory.php
index 4edbead..335d083 100644
--- a/core/lib/Drupal/Core/Config/ConfigFactory.php
+++ b/core/lib/Drupal/Core/Config/ConfigFactory.php
@@ -161,13 +161,16 @@ public function getContext() {
    *   The config factory object.
    */
   public function leaveContext() {
+    // Ensure at least one context is left on the stack. We already ensured
+    // there is at least one context set by taking the initial one in the
+    // constructor.
     if (count($this->contextStack) > 1) {
       array_pop($this->contextStack);
     }
     return $this;
   }
 
-  /*
+  /**
    * Gets the cache key for a given config name in a particular context.
    *
    * @param string $name
diff --git a/core/lib/Drupal/Core/Config/Context/ContextInterface.php b/core/lib/Drupal/Core/Config/Context/ContextInterface.php
index b3107a7..4361bfe 100644
--- a/core/lib/Drupal/Core/Config/Context/ContextInterface.php
+++ b/core/lib/Drupal/Core/Config/Context/ContextInterface.php
@@ -22,7 +22,7 @@
  */
 interface ContextInterface {
 
-  /*
+  /**
    * Initialises a config context for use.
    *
    * Creates a unique context identifier, adds data and notifies system about
diff --git a/core/modules/locale/lib/Drupal/locale/LocaleConfigSubscriber.php b/core/modules/locale/lib/Drupal/locale/LocaleConfigSubscriber.php
index b7b281b..8429d2a 100644
--- a/core/modules/locale/lib/Drupal/locale/LocaleConfigSubscriber.php
+++ b/core/modules/locale/lib/Drupal/locale/LocaleConfigSubscriber.php
@@ -25,6 +25,7 @@
  * $config is always a DrupalConfig object.
  */
 class LocaleConfigSubscriber implements EventSubscriberInterface {
+
   /**
    * The language manager.
    *
@@ -32,6 +33,11 @@ class LocaleConfigSubscriber implements EventSubscriberInterface {
    */
   protected $languageManager;
 
+  /**
+   * Default configuration context.
+   *
+   * @var \Drupal\Core\Config\Context\ContextInterface
+   */
   protected $defaultConfigContext;
 
   /**
@@ -56,7 +62,9 @@ public function __construct(LanguageManager $language_manager, ContextInterface
   public function configContext(ConfigEvent $event) {
     $context = $event->getContext();
 
-    // Add user's language for user context.
+    // If there is a user set in the current context, set the language based on
+    // the preferred language of the user. Otherwise set it based on the
+    // negotiated interface language.
     if ($account = $context->get('user.account')) {
       $context->set('locale.language', language_load(user_preferred_langcode($account)));
     }
@@ -84,6 +92,12 @@ public function configLoad(ConfigEvent $event) {
     }
   }
 
+  /**
+   * Set the negotiated interface language on the default configuration context.
+   *
+   * @param \Symfony\Component\HttpKernel\Event\GetResponseEvent
+   *   Kernel event to respond to.
+   */
   public function onKernelRequestSetDefaultConfigContextLocale(GetResponseEvent $event) {
     if ($language = $this->languageManager->getLanguage(LANGUAGE_TYPE_INTERFACE)) {
       $this->defaultConfigContext->set('locale.language', $language);
diff --git a/core/modules/user/lib/Drupal/user/UserConfigContext.php b/core/modules/user/lib/Drupal/user/UserConfigContext.php
index d6e4114..cd25f19 100644
--- a/core/modules/user/lib/Drupal/user/UserConfigContext.php
+++ b/core/modules/user/lib/Drupal/user/UserConfigContext.php
@@ -34,7 +34,7 @@ public function setUuid() {
     $this->uuid = $this->get(self::USER_KEY)->uuid();
   }
 
-  /*
+  /**
    * Helper function to create config context for user accounts.
    *
    * @param \Drupal\user\Plugin\Core\Entity\User $account