Scalr\Api\Rest\ApiApplication::handleApiVersion PHP Method

    public function handleApiVersion($route)
    {
        $params = $route->getParams();
        if (!preg_match('/^\\d+(beta\\d*)?$/', $params['apiversion'])) {
            throw new ApiErrorException(400, ErrorMessage::ERR_BAD_REQUEST, 'Invalid API version');
        }
        $this->settings[static::SETTING_API_VERSION] = $params['apiversion'];
        unset($params['apiversion']);
        $route->setParams($params);
        //This also parses the named route compound handler
        $options = $route->getDefaults();
        if (!is_callable($options['controller'])) {
            $route->setDefaults(['controller' => $this->getRouteHandler($options['controller'])]);
        }
    }