code: private boolean hasConstraints(ControllerMethod controllerMethod) {
  		Method method = controllerMethod.getMethod();
  		if (method.getParameterTypes().length == 0) {
  			logger.debug("method {} has no parameters, skipping", controllerMethod);
  			return false;
  		}
  		BeanDescriptor bean = bvalidator.getConstraintsForClass(controllerMethod.getController().getType());
  		if(bean == null) {
  			return false;
  		}
  		MethodDescriptor descriptor = bean.getConstraintsForMethod(method.getName(), method.getParameterTypes());
  		return descriptor != null && descriptor.hasConstrainedParameters();
  	}
docs: Only accepts if method isn't parameterless and have at least one constraint.