code: public function serve()
      {
          Log::debug('Request received:', [
              'Method' => $this->request->getMethod(),
              'URI' => $this->request->getRequestUri(),
              'Query' => $this->request->getQueryString(),
              'Protocal' => $this->request->server->get('SERVER_PROTOCOL'),
              'Content' => $this->request->getContent(),
          ]);
  
          $this->validate($this->token);
  
          if ($str = $this->request->get('echostr')) {
              Log::debug("Output 'echostr' is '$str'.");
  
              return new Response($str);
          }
  
          $result = $this->handleRequest();
  
          $response = $this->buildResponse($result['to'], $result['from'], $result['response']);
  
          Log::debug('Server response created:', compact('response'));
  
          return new Response($response);
      }
docs: Handle and return response.
  
  @return Response
  
  @throws BadRequestException