fix label in details element

Closes #3473412

src/Element/ComponentFormBase.php

@@ -22,6 +22,32 @@ abstract class ComponentFormBase extends FormElementBase implements TrustedCallb
     return ['preRenderPropOrSlot', 'processPropOrSlot'];
   }
 
+  /**
+   * Check if the form element needs a details.
+   *
+   * @param array $element
+   *   The form element.
+   *
+   * @return string|null
+   *   Prop or slot id if the form element needs a details.
+   */
+  protected static function checkDetailsElement(array &$element) : ?string {
+    if (!isset($element["#wrap"]) || !$element["#wrap"]) {
+      return NULL;
+    }
+    $prop_or_slot_id = $element["#prop_id"] ?? $element["#slot_id"];
+    $title_in_component = $element["#title_in_component"] ?? $prop_or_slot_id;
+    $title = !empty($element['#title']) ? $element['#title'] : $title_in_component;
+    if (!array_key_exists($prop_or_slot_id, $element)) {
+      $element[$prop_or_slot_id] = [
+        "#type" => "details",
+        "#title" => $title,
+        "#open" => FALSE,
+      ];
+    }
+    return $prop_or_slot_id;
+  }
+
   /**
    * Customize slot or prop form elements (pre-render).
    *
@@ -32,17 +58,8 @@ abstract class ComponentFormBase extends FormElementBase implements TrustedCallb
    *   Processed element
    */
   public static function preRenderPropOrSlot(array $element) : array {
-    if (isset($element["#wrap"]) && $element["#wrap"]) {
-      $prop_or_slot_id = $element["#prop_id"] ?? $element["#slot_id"];
-      $title = !empty($element['#title']) ? $element['#title'] : $prop_or_slot_id;
+    if ($prop_or_slot_id = static::checkDetailsElement($element)) {
       $children_keys = Element::children($element);
-      if (!array_key_exists($prop_or_slot_id, $element)) {
-        $element[$prop_or_slot_id] = [
-          "#type" => "details",
-          "#title" => $title,
-          "#open" => FALSE,
-        ];
-      }
       foreach ($children_keys as $child_key) {
         if ($child_key === $prop_or_slot_id) {
           continue;
@@ -67,17 +84,7 @@ abstract class ComponentFormBase extends FormElementBase implements TrustedCallb
    */
   public static function processPropOrSlot(array &$element, FormStateInterface $form_state) {
     $triggering_element = $form_state->getTriggeringElement();
-    if (isset($element["#wrap"]) && $element["#wrap"]) {
-      $prop_or_slot_id = $element["#prop_id"] ?? $element["#slot_id"];
-      $title = !empty($element['#title']) ? $element['#title'] : $prop_or_slot_id;
-      if (!array_key_exists($prop_or_slot_id, $element)) {
-        $element[$prop_or_slot_id] = [
-          "#type" => "details",
-          "#title" => $title,
-          "#open" => FALSE,
-        ];
-      }
-
+    if ($prop_or_slot_id = static::checkDetailsElement($element)) {
       if (is_array($triggering_element) && isset($triggering_element["#array_parents"]) && is_array($triggering_element["#array_parents"])) {
         $element_array_parents = $element["#array_parents"];
         $trigger_array_parents = $triggering_element["#array_parents"];