code: private void addInstancesToVIPMaps(Application app, Map<String, VipIndexSupport> virtualHostNameAppMap,
              Map<String, VipIndexSupport> secureVirtualHostNameAppMap) {
          // Check and add the instances to the their respective virtual host name
          // mappings
          for (InstanceInfo info : app.getInstances()) {
              String vipAddresses = info.getVIPAddress();
              if (vipAddresses != null) {
                  addInstanceToMap(info, vipAddresses, virtualHostNameAppMap);
              }
  
              String secureVipAddresses = info.getSecureVipAddress();
              if (secureVipAddresses != null) {
                  addInstanceToMap(info, secureVipAddresses, secureVirtualHostNameAppMap);
              }
          }
      }
docs: Adds the instances to the internal vip address map.
  
  @param app
  - the applications for which the instances need to be added.