public function createTask(JobInterface $job)
    {
        $className = $job->getTaskClassName();
        $task = new $className($this, $job->getParams());

        if (!$task instanceof TaskAbstract) {
            throw new \InvalidArgumentException('Task must be an instance of "Extlib\Cron\Task\TaskAbstract", given "%s".', get_class($task));
        }
        
        return $task;
    }