Php siteye Google index api kurulumu yaptım, ancak $link değişkenini kullanamıyorum. Nerede hata yapıyorum acaba.

<?php 
require_once 'autoload.php';

$link = "https://siteadi.net/test-test";

$client = new Google_Client();

// service_account_file.json is the private key that you created for your service account.
$client->setAuthConfig('geopa-346408-287ffcc26f34.json');
$client->addScope('https://www.googleapis.com/auth/indexing');

// Get a Guzzle HTTP Client
$httpClient = $client->authorize();
$endpoint = 'https://indexing.googleapis.com/v3/urlNotifications:publish';

// Define contents here. The structure of the content is described in the next step.
$content = '{
  "url": $link,
  "type": "URL_UPDATED"
}';

$response = $httpClient->post($endpoint, [ 'body' => $content ]);
echo $status_code = $response->getStatusCode();


 ?>