core tests

Closes #3477671

core/tests/Drupal/FunctionalTests/DefaultContent/ContentImportTest.php

@@ -72,6 +72,9 @@ class ContentImportTest extends BrowserTestBase {
     'user',
   ];
 
+  /**
+   * The directory with the source data.
+   */
   private readonly string $contentDir;
 
   /**