Perform the following steps to complete this recipe:

1. First, we create a User Plain Old Java Object (POJO):

public class User implements Serializable{

    private Long id;
    private String name;
    
    public User(long id, String name){
        this.id = id;
        this.name = name;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    
}

2. Then, we create a slow UserBean object to return User:

@Stateless
public class UserBean {
    
    public User getUser(){
        long id = new Date().getTime();

        try {
            TimeUnit.SECONDS.sleep(5);
            return new User(id, "User " + id);
        } catch (InterruptedException ex) {
            System.err.println(ex.getMessage());
            return new User(id, "Error " + id);
        }
    }
}

3. Finally, we create our asynchronous servlet:

@WebServlet(name = "UserServlet", urlPatterns = {"/UserServlet"}, asyncSupported = true)
public class UserServlet extends HttpServlet {

    @Inject
    private UserBean userBean;
    
    private final Jsonb jsonb = JsonbBuilder.create();
    
    @Override
    protected void doGet(HttpServletRequest req, 
    HttpServletResponse resp) throws ServletException, 
    IOException {
        AsyncContext ctx = req.startAsync();
        ctx.start(() -< {
            try (PrintWriter writer = 
            ctx.getResponse().getWriter()){
                writer.write(jsonb.toJson(userBean.getUser()));
            } catch (IOException ex) {
                System.err.println(ex.getMessage());
            }
            ctx.complete();
        });
    }

    @Override
    public void destroy() {
        try {
            jsonb.close();
        } catch (Exception ex) {
         System.err.println(ex.getMessage());
        }
    }

}