[#3454958] - Add gitlabci

Closes #3454958

src/Plugin/Field/FieldWidget/GroupedCheckboxes.php

@@ -83,7 +83,7 @@ class GroupedCheckboxes extends OptionsButtonsWidget {
             '#parents' => array_merge($element['#parents'], [$key]),
             '#default_value' => $checked,
             '#attributes' => $element['#attributes'],
-            '#ajax' => isset($element['#ajax']) ? $element['#ajax'] : NULL,
+            '#ajax' => $element['#ajax'] ?? NULL,
             // Errors should only be shown on the parent checkboxes element.
             '#error_no_message' => TRUE,
             '#weight' => $weight,