Close #2973863: Do not enforce data integrity on pre-existing entity references

Closes #2973863

core/lib/Drupal/Core/Entity/Plugin/Validation/Constraint/ValidReferenceConstraintValidator.php

@@ -119,31 +119,43 @@ public function validate($value, Constraint $constraint): void {
       }
     }
 
-    // Add violations on deltas with a target_id that is not valid.
+    // Don't try to validate pre-existing items.
     if ($target_ids) {
-      // Get a list of pre-existing references.
-      $previously_referenced_ids = [];
       if ($entity && !$entity->isNew()) {
         $existing_entity = $this->entityTypeManager->getStorage($entity->getEntityTypeId())->loadUnchanged($entity->id());
-        foreach ($existing_entity->{$value->getFieldDefinition()->getName()}->getValue() as $item) {
-          $previously_referenced_ids[$item['target_id']] = $item['target_id'];
+        $existing_target_ids = [];
+        if ($existing_entity->isTranslatable()) {
+          foreach ($existing_entity->getTranslationLanguages() as $language) {
+            $existing_entity = $existing_entity->getTranslation($language->getId());
+            foreach ($existing_entity->{$value->getFieldDefinition()->getName()}->getValue() as $item) {
+              $existing_target_ids[$item['target_id']] = $item['target_id'];
+            }
+          }
         }
+        else {
+          foreach ($existing_entity->{$value->getFieldDefinition()
+            ->getName()}->getValue() as $item) {
+            $existing_target_ids[$item['target_id']] = $item['target_id'];
+          }
+        }
+
+        $target_ids = array_diff($target_ids, $existing_target_ids);
       }
+    }
 
+    // Add violations on deltas with a target_id that is not valid.
+    if ($target_ids) {
       $valid_target_ids = $handler->validateReferenceableEntities($target_ids);
       if ($invalid_target_ids = array_diff($target_ids, $valid_target_ids)) {
         // For accuracy of the error message, differentiate non-referenceable
         // and non-existent entities.
-        $existing_entities = $this->entityTypeManager->getStorage($target_type_id)->loadMultiple($invalid_target_ids);
+        $target_type = $this->entityTypeManager->getDefinition($target_type_id);
+        $existing_ids = $this->entityTypeManager->getStorage($target_type_id)->getQuery()
+          ->accessCheck(FALSE)
+          ->condition($target_type->getKey('id'), $invalid_target_ids, 'IN')
+          ->execute();
         foreach ($invalid_target_ids as $delta => $target_id) {
-          // Check if any of the invalid existing references are simply not
-          // accessible by the user, in which case they need to be excluded from
-          // validation
-          if (isset($previously_referenced_ids[$target_id]) && isset($existing_entities[$target_id]) && !$existing_entities[$target_id]->access('view')) {
-            continue;
-          }
-
-          $message = isset($existing_entities[$target_id]) ? $constraint->message : $constraint->nonExistingMessage;
+          $message = in_array($target_id, $existing_ids) ? $constraint->message : $constraint->nonExistingMessage;
           $this->context->buildViolation($message)
             ->setParameter('%type', $target_type_id)
             ->setParameter('%id', $target_id)