diff --git a/core/lib/Drupal/Core/Entity/EntityConstraintViolationList.php b/core/lib/Drupal/Core/Entity/EntityConstraintViolationList.php
index 63ccff4..d20bdf4 100644
--- a/core/lib/Drupal/Core/Entity/EntityConstraintViolationList.php
+++ b/core/lib/Drupal/Core/Entity/EntityConstraintViolationList.php
@@ -143,4 +143,4 @@ public function set($offset, ConstraintViolationInterface $violation) {
     $this->violationsByField = NULL;
   }
 
-}
\ No newline at end of file
+}
diff --git a/core/lib/Drupal/Core/Entity/EntityConstraintViolationListInterface.php b/core/lib/Drupal/Core/Entity/EntityConstraintViolationListInterface.php
index 0be1cb1..1644e99 100644
--- a/core/lib/Drupal/Core/Entity/EntityConstraintViolationListInterface.php
+++ b/core/lib/Drupal/Core/Entity/EntityConstraintViolationListInterface.php
@@ -45,7 +45,7 @@ public function filterByField($field_name);
    * @return \Symfony\Component\Validator\ConstraintViolationListInterface
    *   The list of violations being removed.
    */
-  public function filterByFields($field_names);
+  public function filterByFields(array $field_names);
 
   /**
    * Filters the violations of inaccessible fields.
@@ -78,4 +78,4 @@ public function getViolatedFieldNames();
    */
   public function getEntity();
 
-}
\ No newline at end of file
+}