Why is my servlet creating a JSESSIONID cookie?

I am developing something using Servlets. I create cookies in this program and a cookie is created with the name JSESSIONID, but when I comment on all the code, even then a cookie is created. Here is my code:

CookieDemoServlet.java:

public class CookieDemoServlet extends HttpServlet {

    public void service(HttpServletRequest req, HttpServletResponse res) throws
            ServletException, IOException {

        /*String em = req.getParameter("email");
        Cookie ck[] = req.getCookies();
        if (ck != null) {
            if (ck.length != 0) {
                for (Cookie c : ck) {
                    String cn = c.getName();

                    if (cn.equals("JSESSIONID")) {

                        System.out.println("You are the Old User");
                        String cv = c.getValue();
                        String d = c.getDomain();

                        System.out.println(cn + "\t:" + cv + "\t:" + d);
                    }

                } else {
                    System.out.println("Sorry,No Cookies Found");
                }
            }

            HttpSession session = req.getSession();
            boolean b = session.isNew();
            if (b) {
                System.out.println("You are the New user");
            } else {
                System.out.println("You are the Old User");
            }

            Cookie c1 = new Cookie("Email", em);
            res.addCookie(c1);
            Cookie c2 = new Cookie("Phone", "99999");
            res.addCookie(c2);*/

            RequestDispatcher rd = req.getRequestDispatcher("cookiedemo.jsp");
            rd.forward(req, res);

        }

    }
}

What could be the reason?