spring-cloud-openfeign: @PathVariable is not getting interpolated if the variable is null

@RequestMapping(value = "/items/{id}", method = RequestMethod.PUT)
  ItemResponse updateItem(@PathVariable("id") final Integer id, ItemRequest request);

FeignClient is not throwing any Null pointer exception or Errors when id is null while invoking the above feign client method; it simply send a string {id} to the service, instead of trying to interpolate and fail. This is very misleading IMHO.

My server side was a spring boot app and it had the similar configuration for the PUT endpoint and it went to a http500 with the following exception. java.lang.NumberFormatException: For input string: "{id}"