Issue with response as APPLICATION_XML while using Spring webflux

Question

Following code works fine while returning JSON

public Mono<ServerResponse> postUpload(ServerRequest request) {

final Flux<Object> stringFlux = request.body(BodyExtractors.toParts())
            .flatMap(filePart -> filePart.content().map(dataBuffer -> {
                byte[] bytes = new byte[dataBuffer.readableByteCount()];
                dataBuffer.read(bytes);
                DataBufferUtils.release(dataBuffer);
                byte[] resMessage = new byte[1024];
                resMessage = helper.postUpload(bytes, headers);
                String resposeMessage = new String(resMessage, StandardCharsets.UTF_8);
                return resposeMessage;
            }).doOnError(e -> LOGGER.error("Error on Processing file", e)));
            
    return ServerResponse.ok().contentType(MediaType.APPLICATION_JSON).body(stringFlux, Object.class);
    }

But I get error if I return XML (replaced JSON in the last line with XML)

return ServerResponse.ok().contentType(MediaType.APPLICATION_XML).body(stringFlux, Object.class);

Error message I get is Content type 'application/xml' not supported for bodyType=java.lang.Object

Reviewed similar question at SpringBoot Webflux cannot return application/xml and javax.xml.bind.JAXBException Implementation of JAXB-API has not been found on module path or classpath, accordingly changed my code to use JAXB

JAXBContext jc = null;
            try {
                jc =JAXBContext.newInstance(new Class[]{com.apple.ist.realestate.sm.rqm.model.TestXml.class});
            } catch (JAXBException e1) {
                e1.printStackTrace();
            }
return ServerResponse.ok().contentType(MediaType.APPLICATION_XML).body(BodyInserters.fromValue(jc));

Still I get the unsupported error: Content type 'application/xml' not supported for bodyType=com.sun.xml.bind.v2.runtime.JAXBContextImpl

Any help or discussion appreciated.