docs: @Override
      public List<ServiceInstance> lookupInstances(String serviceName)
              throws ServiceException {
          
          ServiceInstanceUtils.validateManagerIsStarted(isStarted);
          ServiceInstanceUtils.validateServiceName(serviceName);
  
          List<ModelServiceInstance> modelSvc = getLookupService().getUPModelInstances(serviceName);
          List<ServiceInstance> instances = new ArrayList<ServiceInstance>();
          for (ModelServiceInstance modelInstance : modelSvc) {
              instances.add(ServiceInstanceUtils.toServiceInstance(modelInstance));
          }
          return instances;
      }