Issue #3274071: Show non-matching PDF keys when uploading a new PDF to a form

src/Form/FillPdfFormForm.php

@@ -552,7 +552,7 @@ class FillPdfFormForm extends ContentEntityForm {
           '#prefix' => $this->t("These keys couldn't be found in the new PDF:"),
           [
             '#theme' => 'item_list',
-            '#items' => array_keys($non_matching_fields),
+            '#items' => $non_matching_fields,
           ],
         ];
         $this->messenger()->addWarning($this->renderer->render($message));