NPE when generating a link to POST method without RequestBody parameter

[genglefr]

New in 1.0.0.M1

I've written an endpoint that updates an object based on a provided ID (path parameter), and some variables (request parameters):

@PostMapping("entity/{id}")
public ResponseEntity<Void> update(@PathVariable UUID id, @RequestParam String variable)

When I try to generate a HATEOAS link to this resource:

resource.add(linkTo(methodOn(Controller.class).update(resource.getContent().getId(), null)).withRel("update"));

I get a NPE because my endpoint has POST method, but no RequestBody parameter, and thus following line (PropertyUtils.java:86) raises a NPE:

if (resolvableType.getRawClass().equals(EntityModel.class)) {

Stack trace is like:

java.lang.NullPointerException: null
	at org.springframework.hateoas.mediatype.PropertyUtils.findPropertyNames(PropertyUtils.java:86) ~[spring-hateoas-1.0.0.M1.jar:1.0.0.M1]
	at org.springframework.hateoas.mediatype.collectionjson.CollectionJsonAffordanceModel.determineInputs(CollectionJsonAffordanceModel.java:69) ~[spring-hateoas-1.0.0.M1.jar:1.0.0.M1]
	at org.springframework.hateoas.mediatype.collectionjson.CollectionJsonAffordanceModel.<init>(CollectionJsonAffordanceModel.java:55) ~[spring-hateoas-1.0.0.M1.jar:1.0.0.M1]
	at org.springframework.hateoas.mediatype.collectionjson.CollectionJsonAffordanceModelFactory.getAffordanceModel(CollectionJsonAffordanceModelFactory.java:42) ~[spring-hateoas-1.0.0.M1.jar:1.0.0.M1]
	at org.springframework.hateoas.Affordance.<init>(Affordance.java:67) ~[spring-hateoas-1.0.0.M1.jar:1.0.0.M1]
	at org.springframework.hateoas.server.core.SpringAffordanceBuilder.create(SpringAffordanceBuilder.java:77) ~[spring-hateoas-1.0.0.M1.jar:1.0.0.M1]
	at org.springframework.hateoas.server.core.WebHandler.lambda$linkTo$0(WebHandler.java:146) ~[spring-hateoas-1.0.0.M1.jar:1.0.0.M1]
	at org.springframework.hateoas.server.mvc.WebMvcLinkBuilderFactory.linkTo(WebMvcLinkBuilderFactory.java:125) ~[spring-hateoas-1.0.0.M1.jar:1.0.0.M1]
	at org.springframework.hateoas.server.mvc.WebMvcLinkBuilder.linkTo(WebMvcLinkBuilder.java:174) ~[spring-hateoas-1.0.0.M1.jar:1.0.0.M1]

Issue raised since I updated to 1.0.0.M1.
Same code used to work in previous versions.

[odrotbohm]

I see this code has been guarded against null raw types in the latest snapshots. Would you mind trying 1.0.0.BUILD-SNAPSHOT?

[genglefr]

I'm using Spring Boot 2.2.0.M1 and thus it's difficult to test 1.0.0.BUILD-SNAPSHOT now, as it breaks several dependencies.
I'll confirm your thoughts and close the issue once a new Spring Boot milestone is available.

[odrotbohm]

@genglefr – I know it's short notice but do you still see this issue on the latest releases? The latest Boot milestones should already include fixed versions. We're shooting for the GA release tomorrow and would like to verify.

[gregturn]

I just crafted a test case in WebFlux, and verified this problem doesn't occur anymore.

[genglefr]

I confirm the issue is closed.