XML Stack Overflow

I am working on an API that will primary return JSON but I also want it to return XML if the client prefers to work with XML.

My controller is included below.

I can get JSON and XML to return for http://ift.tt/1wo44cp

However http://ift.tt/1wo44cp work with JSON only, XML returns HttpMediaTypeNotAcceptableException: could not find acceptable representation.

Is this because I'm trying to serialize a List<> to XML? What is the solution to work around?

package net.jkratz.bloodpressure.api.controller;

import net.jkratz.bloodpressure.api.model.Gender;
import net.jkratz.bloodpressure.api.repository.GenderRepository;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import javax.inject.Inject;
import java.util.List;

@RestController
@RequestMapping(value = "/gender", produces = {"application/json","application/xml"})
public class GenderController {

    @Inject
    GenderRepository genderRepository;

    private Logger logger = LoggerFactory.getLogger(getClass());

    @RequestMapping(value = {"","/"}, method = RequestMethod.GET)
    public ResponseEntity<List<Gender>> getGenders(@RequestHeader("Accept") String acceptHeader) {
        logger.info("Serving resource for Accept header: {}", acceptHeader);
        List<Gender> genders = genderRepository.findAll();
        return new ResponseEntity<>(genders, HttpStatus.OK);
    }

    @RequestMapping(value = "/{id}", method = RequestMethod.GET)
    public ResponseEntity<Gender> getGender(@PathVariable("id") Integer id, @RequestHeader("Accept") String acceptHeader) {
        logger.info("Serving resource for Accept header: {}", acceptHeader);
        return new ResponseEntity<>(genderRepository.findOne(id), HttpStatus.OK);
    }
}