diff --git a/core/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php b/core/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php
index aaf47437665933b90b6b46b76dd7d6d369a5e6a5..dac8a5f26ca3ae49d2fd3fbd509b40d6bf183166 100644
--- a/core/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php
+++ b/core/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php
@@ -19,7 +19,7 @@ interface DiscoveryInterface {
    * @param string $plugin_id
    *   A plugin id.
    *
-   * @return array|null
+   * @return mixed
    *   A plugin definition, or NULL if no definition was found for $plugin_id.
    */
   public function getDefinition($plugin_id);
@@ -27,7 +27,7 @@ public function getDefinition($plugin_id);
   /**
    * Gets the definition of all plugins for this type.
    *
-   * @return array
+   * @return mixed[]
    *   An array of plugin definitions (empty array if no definitions were
    *   found).
    */