code: public Session session(boolean create) {
          if (session == null || !validSession) {
              HttpSession httpSession = servletRequest.getSession(create);
              if (httpSession != null) {
                  validSession(true);
                  session = new Session(httpSession, this);
              } else {
                  session = null;
              }
          }
          return session;
      }
docs: Returns the current session associated with this request, or if there is
  no current session and <code>create</code> is true, returns  a new session.
  
  @param create <code>true</code> to create a new session for this request if necessary;
  <code>false</code> to return null if there's no current session
  @return the session associated with this request or <code>null</code> if
  <code>create</code> is <code>false</code> and the request has no valid session