Spring Spring MVC raises MissingPathVariableException resulting in 500 instead of 400 error when path segment is u001F or u00D and cannot be converted to target type UUID

This is an corner case, discovered while performing some property-based testing for my API.

Affects spring-web:6.0.12

Here is a minimal code sample that reproduces the issue

https://gist.github.com/ltsallas/9903343b6b7a90013cdd155bfcd670ce

I think the the last two tests in the DemoControllerTest should return a 400(MethodArgumentTypeMismatchException) and not a 500(MissingPathVariableException) response.

Comment From: rstoyanchev

This case where a value is present, but becomes null after conversion (StringToUUIDConverter calls UUID.fromString) was addressed in #26679. We now detect it and raise MissingPathVariableException, which is what we do generally with missing path variables since that could be an incorrectly defined URI template.

That said in this case a value is present, but not valid and indeed should be treated as a 400. As part of #26679 we did add a missingAfterConversion flag to MissingRequestValueException and could use that to differentiate this case from the more general case of a missing path variable.

Comment From: ltsallas

Thanks for taking a look into this one @rstoyanchev Are you suggesting this change in the getStatusCode() of the MissingPathVariableException ? java @Override public HttpStatusCode getStatusCode() { return isMissingAfterConversion() ? super.getStatusCode() : HttpStatus.INTERNAL_SERVER_ERROR; }