Spring Cloud Openfeign Request Parameter Empty Set translated as "null"

Describe the bug

When an empty set is provided in the request parameters it gets translated as null

Sample

 @GetMapping(value = QUOTES, produces = APPLICATION_JSON_VALUE)
 Set<Quote> getQuotes(@RequestParam(QUOTE_IDS) final Set<UUID> quoteIds);

request:

http://quoting-service/quotes?ids=null

Comment From: StefanTirea

When sending an empty String Set, the receiver gets this: {"null"}.

Comment From: OlgaMaciaszek

@sergio-marshmallow thanks for reporting it. Was able to reproduce this.

Comment From: sergio-marshmallow

@olegz thanks for looking into this 🙂

Comment From: OlgaMaciaszek

Caused by this code.

Comment From: OlgaMaciaszek

@sergio-marshmallow since the issue is directly related to how Feign handles expanding iterable values and is not specific to how Spring annotations are handled, this should probably be opened in https://github.com/OpenFeign/feign, though.

Comment From: StefanTirea

@OlgaMaciaszek thank you for looking into this. I checked the OpenFeign Repo and they came to the same conclusion 12 days ago. They are working on fix and should be merged in the near future.