@Before
    public void init() throws JAXBException {
        user = new User("testUser");

        integerUserMap = new IntegerUserMap();
        for (int i = 0; i < 3; i++) {
            IntegerUserEntry integerUserEntry = new IntegerUserEntry();
            integerUserEntry.setId(i);
            integerUserEntry.setUser(new User("testUser" + i));
            integerUserMap.getEntries().add(integerUserEntry);
        }

        responseType = new ResponseType<User>(0, "this is error message...", user);

        jaxbContext = JAXBContext.newInstance(User.class, IntegerUserMap.class, ResponseType.class);
        marshaller = jaxbContext.createMarshaller();
    }