protected function addJobToQueue(string $jobName, string $payload = '') : string
    {
        if (!isset($this->jobQueues[$jobName])) {
            $this->jobQueues[$jobName] = [];
        }
        $jobId = $this->getJobId();
        array_push($this->jobQueues[$jobName], [
            'job_id' => $jobId,
            'payload' => $payload
        ]);
        $this->jobsInQueue++;
        return $jobId;
    }