Spring No primary or single unique constructor found for interface org.springframework.http.codec.multipart.FilePart

I have a @RestController with the method

@PostMapping 
fun uploadDocument(@Valid data: UploadData, exchange: ServerWebExchange)

where UploadData contains a field

@field:NotNull(message = "file must not be null") private val file: FilePart?

Before the upgrade to Spring Boot 3.2.0, the Bean Validation worked as expected if "file" was missing in the request body. Since the Spring upgrade, I get the exception "No primary or single unique constructor found for interface org.springframework.http.codec.multipart.FilePart" instead.

Comment From: snicoll

Thanks for the report, this is a duplicate of #31669.

Comment From: sbrannen

And potentially a duplicate of #31778, if the affected code is using WebFlux instead of MVC.