Implementing type safe method call to DateTime::setTimestamp()

When loading serialized snapshot contents, this Transformer passes string values to the \DateTime::setTimestamp()" method, resulting in an uncaught FatalThrowableError:

Uncaught PHP Exception Symfony\Component\Debug\Exception\FatalThrowableError: "Type error: DateTime::setTimestamp() expects parameter 1 to be integer, string given" at Transformer.php line 165

Example call (taken from my Symfony Exception page):
DateTime->setTimestamp('1510846884')
in vendor/sonata-project/page-bundle/src/Entity/Transformer.php (line 165)

Author: Jan Petersen

src/Entity/Transformer.php

@@ -161,11 +161,11 @@ public function load(SnapshotInterface $snapshot)
         $page->setRequestMethod($content['request_method']);
 
         $createdAt = new \DateTime();
-        $createdAt->setTimestamp($content['created_at']);
+        $createdAt->setTimestamp((int) $content['created_at']);
         $page->setCreatedAt($createdAt);
 
         $updatedAt = new \DateTime();
-        $updatedAt->setTimestamp($content['updated_at']);
+        $updatedAt->setTimestamp((int) $content['updated_at']);
         $page->setUpdatedAt($updatedAt);
 
         return $page;
@@ -189,11 +189,11 @@ public function loadBlock(array $content, PageInterface $page)
         $block->setType($content['type']);
 
         $createdAt = new \DateTime();
-        $createdAt->setTimestamp($content['created_at']);
+        $createdAt->setTimestamp((int) $content['created_at']);
         $block->setCreatedAt($createdAt);
 
         $updatedAt = new \DateTime();
-        $updatedAt->setTimestamp($content['updated_at']);
+        $updatedAt->setTimestamp((int) $content['updated_at']);
         $block->setUpdatedAt($updatedAt);
 
         foreach ($content['blocks'] as $child) {