docs: @Override
      public List<ModelServiceInstance> getServiceInstanceList() {
          List<ModelServiceInstance> instances = null;
          String keyName = null;
          if (query.getCriteria().size() > 0) {
              keyName = query.getCriteria().get(0).getMetadataKey();
          }
          if (keyName != null && !keyName.isEmpty()) {
              List<ModelServiceInstance> modelInstances = getLookupService()
                      .queryUPModelInstances(query);
              instances = ServiceInstanceQueryHelper
                      .filter(query, modelInstances);
          }
  
          if (instances != null) {
              return instances;
          } else {
              return Collections.emptyList();
          }
      }