Filename encoding is wrong in MultipartFormDataInput with RestEasy and Wildfly 11

My upload rest method works fine unless the filename contains a special character:

    @POST
    @Consumes({ MediaType.MULTIPART_FORM_DATA })
    public Response uploadFile(MultipartFormDataInput input) {
    	Map<String, List<InputPart>> uploadForm = input.getFormDataMap();
    	List<InputPart> inputParts = uploadForm.get("file_upload");
        // Do Stuff...
    }

The filename is *Test.png*, inputPart.getHeaders() = [Content-Disposition=form-data; name="tws_file"; filename="test.png",Content-Type=image/png]
--> OK

The filename is *Döner.png*, inputPart.getHeaders() = [Content-Disposition=form-data; name="tws_file"; filename="d��ner.png",Content-Type=image/png]
--> Not OK

As you can see, the "ö" becomes "��".I am using Wildfly 11 and Resteasy-multipart-provider 3.0.24.Final