break;
                }

                if (nextHead != null) {
                    // prepare remaining
                    // (e.g. set session/tree/fileid returned by the previous requests)
                    resp.prepare(nextHead);
                }
                curHead = nextHead;
            } finally {
                CommonServerMessageBlockRequest curReq = thisReq;

     * @param map the map
     * @param key the key with which the specified value is to be associated
     * @param value the value to be associated with the specified key
     * @return the previous value associated with the specified key, or the specified value if the key was not present
     * @see ConcurrentHashMap#putIfAbsent(Object, Object)
     */