VMWare check if vCenter is working

only for vCenter 7.x

try {
    Zabbix.log(4, 'vc health check');
    var result, resp, url = "{$VMWARE.URL}".replace('/sdk','');
    var req = new HttpRequest();
    req.setHttpAuth(HTTPAUTH_BASIC, "{$VMWARE.USERNAME}", "{$VMWARE.PASSWORD}");
    resp = req.post(url + '/api/session');
    if (req.getStatus() != 201) {
         throw 'Response code: '+req.getStatus();
    }
    req.addHeader("vmware-api-session-id: " + resp.replace('"','').replace('"',''));
    result = req.get(url + '/api/appliance/health/system');
    if (req.getStatus() != 200) {
         throw 'Response code: '+req.getStatus();
    }
    req.delete(url + '/api/session');
} catch (error) {
   Zabbix.log(4, 'vmware call failed : '+error);
   result ='vmware call failed : '+error;
}
return result;

does not work with vCenter 6