code: private static String serviceName(Class<?> serviceInterface) {
      // Service name
      Service serviceAnnotation = serviceInterface.getAnnotation(Service.class);
      requireNonNull(
          serviceAnnotation != null, String.format("Not a service interface: %s", serviceInterface));
      return isNullOrEmpty(serviceAnnotation.value())
          ? serviceInterface.getName()
          : serviceAnnotation.value();
    }
docs: Util function to extract service name from service api.
  
  @param serviceInterface with @Service annotation.
  @return service name.