code: private synchronized QueueBuffer getQBuffer(String qUrl) {
          QueueBuffer toReturn = buffers.get(qUrl);
          if (null == toReturn) {
              QueueBufferConfig config = new QueueBufferConfig(bufferConfigExemplar);
              toReturn = new QueueBuffer(config, qUrl, realSQS);
              buffers.put(qUrl, toReturn);
          }
          return toReturn;
      }
docs: Returns (creating it if necessary) a queue buffer for a particular queue Since we are only
  storing a limited number of queue buffers, it is possible that as a result of calling this
  method the least recently used queue buffer will be removed from our queue buffer cache
  
  @return a queue buffer associated with the provided queue URL. Never null