MAGETWO-58692: Refactor Module_Webapi, Module_Elasticsearch

Introducing SerializerInterface

app/code/Magento/Webapi/Model/Config.php

@@ -52,6 +52,7 @@ class Config
      *
      * @param WebapiCache $cache
      * @param Reader $configReader
+     * @param SerializerInterface|null $serializer
      */
     public function __construct(
         WebapiCache $cache,

app/code/Magento/Webapi/Model/ServiceMetadata.php

@@ -88,6 +88,7 @@ class ServiceMetadata
      * @param WebApiCache $cache
      * @param \Magento\Webapi\Model\Config\ClassReflector $classReflector
      * @param \Magento\Framework\Reflection\TypeProcessor $typeProcessor
+     * @param SerializerInterface|null $serializer
      */
     public function __construct(
         \Magento\Webapi\Model\Config $config,