$serviceAccount = ServiceAccount::fromJsonFile(__DIR__.'/google.json');

$firebase = (new Factory)
        ->withServiceAccount($serviceAccount)
        // The following line is optional if the project id in your credentials file
        // is identical to the subdomain of your Firebase project. If you need it,
        // make sure to replace the URL with the URL of your project.
        //->withDatabaseUri('https://my-project.firebaseio.com')
        ->create();

$messaging = $firebase->getMessaging();

$deviceToken = 'token';

$notification = Notification::create("test", "body");
$data = [
   'first_key' => 'First Value',
   'second_key' => 'Second Value',
];

$message = CloudMessage::withTarget('token', $deviceToken)
     ->withNotification($notification) // optional
     ->withData($data);

// error here
// 404 Client error: `POST https://fcm.googleapis.com/v1/projects/projectid/messages:send` resulted in a `404 Not Found
$messaging->send($message);