code: private Object retrieveLock(String key)
     {
        Object lock = this.lockMap.get(key);
        if(lock == null)
        {
           lock = key;
           this.lockMap.put(key, lock);
        }
        return lock;
     }
docs: Retrieve the lock object for a given key
  @param key the key for the lock
  @return the object that will be used as a lock