Issue #3040556: It is not possible to react to an entity being duplicated

Initial quick solution without creating hook support and move logic into entity storage.

core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php

@@ -215,12 +215,11 @@ public function isUninstalling() {
   /**
    * {@inheritdoc}
    */
-  public function createDuplicate() {
-    $duplicate = parent::createDuplicate();
+  public function postDuplicate(EntityStorageInterface $storage) {
+    parent::postDuplicate();
 
     // Prevent the new duplicate from being misinterpreted as a rename.
-    $duplicate->setOriginalId(NULL);
-    return $duplicate;
+    $this->setOriginalId(NULL);
   }
 
   /**