@XmlJavaTypeAdapter(LocalDateTimeAdapter.class)

 ---------------------

public class LocalDateTimeAdapter extends XmlAdapter<String, LocalDateTime> {
    @Override
    public LocalDateTime unmarshal(String s) throws Exception {
        return LocalDateTime.parse(s, DateTimeFormatter.ofPattern("yyyy/MM/dd' 'HH:mm:ss"));
    }

    @Override
    public String marshal(LocalDateTime localDateTime) throws Exception {
        return localDateTime.toString();
    }
}