code: public static <K, V> ConcurrentMap<K, V> getMapSessionAttribute(
              HttpSession session, String name) {
          return getMapSessionAttribute(session, name, true);
      }
docs: Get a {@link ConcurrentMap} for the specified name from the {@link HttpSession} attributes.
  If it doesn't exist create it and store it in the attributes. This is done in a thread-safe
  matter that ensures only one Map per name & session will be created @See {@link
  WebUtils#getSessionMutex(HttpSession)}