diff --git a/core/lib/Drupal/Core/Config/ConfigInstaller.php b/core/lib/Drupal/Core/Config/ConfigInstaller.php
index 6cf244b861e..66ebcedd5e1 100644
--- a/core/lib/Drupal/Core/Config/ConfigInstaller.php
+++ b/core/lib/Drupal/Core/Config/ConfigInstaller.php
@@ -379,11 +379,7 @@ class ConfigInstaller implements ConfigInstallerInterface {
   }
 
   /**
-   * Gets the configuration storage that provides the default configuration.
-   *
-   * @return \Drupal\Core\Config\StorageInterface|null
-   *   The configuration storage that provides the default configuration.
-   *   Returns null if the source storage has not been set.
+   * {@inheritdoc}
    */
   public function getSourceStorage() {
     return $this->sourceStorage;
diff --git a/core/lib/Drupal/Core/Config/ConfigInstallerInterface.php b/core/lib/Drupal/Core/Config/ConfigInstallerInterface.php
index 41b015e61bb..aae9474a52f 100644
--- a/core/lib/Drupal/Core/Config/ConfigInstallerInterface.php
+++ b/core/lib/Drupal/Core/Config/ConfigInstallerInterface.php
@@ -75,6 +75,15 @@ interface ConfigInstallerInterface {
    */
   public function setSourceStorage(StorageInterface $storage);
 
+  /**
+   * Gets the configuration storage that provides the default configuration.
+   *
+   * @return \Drupal\Core\Config\StorageInterface|null
+   *   The configuration storage that provides the default configuration.
+   *   Returns null if the source storage has not been set.
+   */
+  public function getSourceStorage();
+
   /**
    * Sets the status of the isSyncing flag.
    *