When there are no site-resource is configured
then vnfid is null
Issue-ID: HOLMES-194
Change-Id: I275ab60b20ca2ea0fe1ced9ce2b9ef0f99875c15
Signed-off-by: Rama-Huawei <rama.subba.reddy.s@huawei.com>
 
     public JSONObject getSiteServiceInstance(String siteService) throws CorrelationException {
         String vnfId = getSiteVNFId(siteService);
+        if (vnfId == null) {
+            return null;
+        }
         JSONObject serviceInstanceInfo = getServiceInstanceByVnfId(vnfId);
         String serviceInstancePath = serviceInstanceInfo.getString("related-link");
         Response response = get(getHostAddr(), getPath(serviceInstancePath));