docs: public List<InstanceInfo> getInstancesBySecureVirtualHostName(String secureVirtualHostName) {
          return Optional.ofNullable(this.secureVirtualHostNameAppMap.get(secureVirtualHostName.toUpperCase(Locale.ROOT)))
                  .map(VipIndexSupport::getVipList)
                  .map(AtomicReference::get)
                  .orElseGet(Collections::emptyList);        
      }