PayPal\Api\InvoiceItem::setImageUrl PHP Méthode

    public function setImageUrl($image_url)
    {
        UrlValidator::validate($image_url, "ImageUrl");
        $this->image_url = $image_url;
        return $this;
    }

 /**
  * @expectedException \InvalidArgumentException
  * @expectedExceptionMessage ImageUrl is not a fully qualified URL
  */
 public function testUrlValidationForImageUrl()
 {
     $obj = new InvoiceItem();
     $obj->setImageUrl(null);
 }