Issue #3441909: In CKEditor 5, LinkIt is incompatible with Media Entity...

Issue #3441909: In CKEditor 5, LinkIt is incompatible with Media Entity Download because it doesn't tell CKEditor about required data attributes on the <a> tag

src/Plugin/CKEditor5Plugin/Linkit.php

@@ -6,7 +6,7 @@ namespace Drupal\linkit\Plugin\CKEditor5Plugin;
 
 use Drupal\ckeditor5\Plugin\CKEditor5PluginConfigurableTrait;
 use Drupal\ckeditor5\Plugin\CKEditor5PluginDefault;
-use Drupal\ckeditor5\Plugin\CKEditor5PluginConfigurableInterface;
+use Drupal\ckeditor5\Plugin\CKEditor5PluginElementsSubsetInterface;
 use Drupal\Core\Entity\EntityStorageInterface;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
@@ -18,7 +18,7 @@ use Symfony\Component\Validator\Context\ExecutionContextInterface;
 /**
  * CKEditor 5 Linkit plugin configuration.
  */
-class Linkit extends CKEditor5PluginDefault implements CKEditor5PluginConfigurableInterface, ContainerFactoryPluginInterface {
+class Linkit extends CKEditor5PluginDefault implements CKEditor5PluginElementsSubsetInterface, ContainerFactoryPluginInterface {
 
   use CKEditor5PluginConfigurableTrait;
 
@@ -49,6 +49,14 @@ class Linkit extends CKEditor5PluginDefault implements CKEditor5PluginConfigurab
     );
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getElementsSubset(): array {
+    // @see \Drupal\linkit\Plugin\Filter\LinkitFilter
+    return ['<a data-entity-type data-entity-uuid data-entity-substitution>'];
+  }
+
   /**
    * {@inheritdoc}
    */