diff --git a/src/Service/UWServiceInterface.php b/src/Service/UWServiceInterface.php
index 4491b9d0babd8fd564756f6497f4e9bdcbdb5380..1311d7f9ed1bd64d28db4df41ac923db1349f19d 100644
--- a/src/Service/UWServiceInterface.php
+++ b/src/Service/UWServiceInterface.php
@@ -200,6 +200,8 @@ interface UWServiceInterface {
    *
    * @param array $content_types
    *   Array of content types.
+   * @param bool $show_null_content_types
+   *   Flag to show null content type usage.
    *
    * @return array
    *   Array of content type usage.