diff --git a/core/lib/Drupal/Core/Entity/EntityCreateAccessCheck.php b/core/lib/Drupal/Core/Entity/EntityCreateAccessCheck.php
index 9110f69..62015f2 100644
--- a/core/lib/Drupal/Core/Entity/EntityCreateAccessCheck.php
+++ b/core/lib/Drupal/Core/Entity/EntityCreateAccessCheck.php
@@ -57,11 +57,29 @@ public function access(Route $route, Request $request) {
     if ($bundle && isset($definition['entity_keys']['bundle'])) {
       $values[$definition['entity_keys']['bundle']] = $bundle;
     }
+    // Allow further manipulation of the entity values.
+    $values = $this->prepareEntityValues($values, $definition, $request);
     $entity = $this->entityManager->getStorageController($entity_type)
       ->create($values);
 
     return $this->entityManager->getAccessController($entity_type)->access($entity, 'create');
   }
 
+  /**
+   * Performs further manipulation of the entity values.
+   *
+   * @param array $values
+   *   The values to be passed to \Drupal\Core\Entity\EntityInterface::create().
+   * @param array $definition
+   *   The entity type definition.
+   * @param \Symfony\Component\HttpFoundation\Request $request
+   *   The request object.
+   *
+   * @return array
+   *   The modified values to be used to create the entity.
+   */
+  protected function prepareEntityValues(array $values, array $definition, Request $request) {
+    return $values;
+  }
 
 }