code: public static ResourceService getResourceService() {
      if (resourceService == null) {
        try {
          Class clazz = Class.forName(RESOURCE_SERVICE);
          resourceService = (ResourceService) clazz.newInstance();
        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException e) {
          LOGGER.warn("Cannot instanciate util: {}", e.getMessage());
          throw new IllegalStateException(e);
        }
      }
      return resourceService;
    }
docs: Retrieve ResourceService implementation
  @return ResourceService instance