@XmlRootElement
public class JerseyObject implements Serializable {

    String name;
}

@Controller
@RequestMapping("/sample")
public class SampleController {

    @GetMapping(produces = MediaType.APPLICATION_XML_VALUE)
    public ResponseEntity<JerseyObject> get() {
        return ResponseEntity.ok(new JerseyObject("Name"));
    }
}

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<jerseyObject>
    <name>Name</name>
</jerseyObject>