code: public function post(Payload $payload, $endpoint)
      {
          if (! Type::isValidWebhookType($payload->getAction())) {
              throw new \Exception(sprintf('Webhook "%s" isn\'t valid', $payload->getAction()));
          }
  
          $requestContent = [
              'headers' => ['Content-Type' => 'application/json'],
              'body'    => json_encode($payload),
              'timeout' => self::DEFAULT_REQUEST_TIMEOUT
          ];
  
          return $this->guzzleClient->post($endpoint, $requestContent);
      }
docs: Makes a request identical to the Emailbidding webhook event
  
  @param Payload $payload The Emailbidding payload
  @param string  $endpoint The endpoint where to the Emailbidding payload should be sent
  
  @return \Psr\Http\Message\ResponseInterface
  @throws \Exception An exception if the payload has errors