public function execute(Request $request): Response
    {
        $method = $request->getMethod();
        list($resp, $grpcStatus) = $request->getClient()->$method(
            $request->getMessage(),
            $request->getMetadata(),
            $request->getOptions()
        )->wait();

        $headers = new HeaderCollection();

        if (is_null($grpcStatus)) { // in the very bad case even this fails to return
            $status = new Error\Status(\Grpc\STATUS_UNKNOWN, '', $headers);
        } else {
            $metadata = $grpcStatus->metadata;
            foreach ($metadata as $k => $v) {
                if (is_array($v)) {
                    foreach ($v as $v2) {
                        $headers->add($k, $v2);
                    }
                } else {
                    $headers->add($k, $v);
                }
            }
            $status = new Error\Status(intval($grpcStatus->code), strval($grpcStatus->details), $headers);
        }

        if (is_null($resp)) {
            $request->fail($status);
        }

        return $request->succeed($resp, $status);
    }