public function getUser(): User
    {
        if ($this->sender !== null) {
            return $this->sender;
        }

        $userId = (string) $this->request->getParameter('object.user_id');
        $request = $this->http->get(self::API_URL.'users.get', [
            'query' => [
                'user_ids' => $userId,
                'v' => self::API_VERSION,
            ],
        ]);
        $response = json_decode($request->getBody()->getContents(), true);
        $user = $response['response'][0];

        return $this->sender = new User(
            (string) $user['id'],
            $user['first_name'].' '.$user['last_name']
        );
    }