feat: Add the protected apiVersion property

src/Service/Resource.php

@@ -48,6 +48,9 @@ class Resource
     /** @var string $rootUrl */
     private $rootUrl;
 
+    /** @var string $apiVersion */
+    protected $apiVersion;
+
     /** @var \Google\Client $client */
     private $client;
 
@@ -235,6 +238,13 @@ public function call($name, $arguments, $expectedClass = null)
             return $request;
         }
 
+        // If the class which is extending from this one contains
+        // an Api Version, add it to the header
+        if ($this->apiVersion) {
+            $request = $request
+                ->withHeaders('X-Goog-Api-Version', $this->apiVersion);
+        }
+
         return $this->client->execute($request, $expectedClass);
     }