Specifically ask for the Json Serializer object and not just relying on the interface that could change

Author: dmanners

app/code/Magento/Braintree/Gateway/Response/VaultDetailsHandler.php

@@ -42,32 +42,33 @@ class VaultDetailsHandler implements HandlerInterface
     protected $config;
 
     /**
-     * @var \Magento\Framework\Serialize\SerializerInterface
+     * @var \Magento\Framework\Serialize\Serializer\Json
      */
     private $serializer;
 
     /**
-     * Constructor
+     * VaultDetailsHandler constructor.
      *
      * @param PaymentTokenInterfaceFactory $paymentTokenFactory
      * @param OrderPaymentExtensionInterfaceFactory $paymentExtensionFactory
      * @param Config $config
      * @param SubjectReader $subjectReader
-     * @param \Magento\Framework\Serialize\SerializerInterface $serializer
+     * @param \Magento\Framework\Serialize\Serializer\Json|null $serializer
+     * @throws \RuntimeException
      */
     public function __construct(
         PaymentTokenInterfaceFactory $paymentTokenFactory,
         OrderPaymentExtensionInterfaceFactory $paymentExtensionFactory,
         Config $config,
         SubjectReader $subjectReader,
-        \Magento\Framework\Serialize\SerializerInterface $serializer = null
+        \Magento\Framework\Serialize\Serializer\Json $serializer = null
     ) {
         $this->paymentTokenFactory = $paymentTokenFactory;
         $this->paymentExtensionFactory = $paymentExtensionFactory;
         $this->config = $config;
         $this->subjectReader = $subjectReader;
         $this->serializer = $serializer ?: \Magento\Framework\App\ObjectManager::getInstance()
-            ->get(\Magento\Framework\Serialize\SerializerInterface::class);
+            ->get(\Magento\Framework\Serialize\Serializer\Json::class);
     }
 
     /**

app/code/Magento/Braintree/Test/Unit/Gateway/Response/VaultDetailsHandlerTest.php

@@ -123,7 +123,7 @@ protected function setUp()
             ->willReturn($mapperArray);
 
         $this->serializer = $this->getMock(
-            \Magento\Framework\Serialize\SerializerInterface::class,
+            \Magento\Framework\Serialize\Serializer\Json::class,
             [],
             [],
             '',