protected function setProperties()
    {
        // Fetch request query string values passed by an API client.
        list($limit, $offset) = $this->paramBag->get('limit');
        list($sortKey, $sortDirection) = $this->paramBag->get('sort');

        // If nothing is passed by API client,
        // falling back to class property's value.
        $this->limit = $limit ?: $this->limit;
        $this->offset = $offset ?: $this->offset;
        $this->sortKey = $sortKey ?: $this->sortKey;
        $this->sortDirection = $sortDirection ?: $this->sortDirection;
    }