Enum Multipart parameter

[Thomas Butz]

I'm currently struggling with the following snippet which used to work with 
TomEE 8.x but fails on 9.1.2:

@POST
@Path("/documents/{type}/by-id/{id}")
@Consumes(MediaType.MULTIPART_FORM_DATA)
@Produces(MediaType.APPLICATION_JSON)
public Response postWithId(@PathParam("type") String type, @PathParam("id") int 
id,
                                        @Multipart(value = "file") Attachment 
attachment,
                                        @Multipart(value = "category") 
DocumentCategory category,
                                        @Multipart(value = "description", 
required = false) String description) {
      // ...
}

DocumentCategory is an Enum. A POST request with an example file and the 
category set to "GENERIC" invokes the function with the category parameter set 
to "null".

Doing things by hand works just fine, though:

@POST
@Path("/documents/{type}/by-id/{id}")
@Consumes(MediaType.MULTIPART_FORM_DATA)
@Produces(MediaType.APPLICATION_JSON)
public Response postWithId(@PathParam("type") String type, @PathParam("id") int 
id,
                                        @Multipart(value = "file") Attachment 
attachment,
                                        @Multipart(value = "category") String 
category,
                                        @Multipart(value = "description", 
required = false) String description) {
      DocumentCategory cat = DocumentCategory.valueOf(cat);
      // ...
}

Am I missing something here?