code: private HttpSession doGetSession(boolean create) {
          if (session == null) {
              Cookie cookie = WebUtil.findCookie(this, getSessionCookieName());
              if (cookie != null) {
                  String value = cookie.getValue();
                  log.debug("discovery session id from cookie: {}", value);
                  session = buildSession(value, false);
              } else {
                  session = buildSession(create);
              }
          } else {
              log.debug("Session[{}] was existed.", session.getId());
          }
          return session;
      }
docs: get session from session cookie name
  @param create if true create
  @return session