code: public function getRefund($request)
      {
          if (is_array($request)) {
              $request = RequestCreator::create(GetSubscriptionRequest::class, $request);
          } else if (!($request instanceof GetRefundRequest)) {
              $request = new GetRefundRequest($request);
          }
  
          ObjectRecursiveValidator::validate($request);
          $serializer = new GetRefundSerializer($request);
          $transport = new GetRefundTransport($serializer);
  
          return $this->execute($transport, GetRefundResponse::class);
      }
docs: @param string|array|GetRefundRequest $request
  
  @return AbstractResponse|GetRefundResponse
  @throws ResponseException
  @throws TransportException