code: public BlockingQueue<CollectionDocument> getQueue(String queueName) {
  		Preconditions.checkArgument(registry.containsKey(queueName), "Queue %s does not exist", queueName);
  		return registry.get(queueName);
  	}
docs: Retrieves and returns a registered queue by name.
  
  @param queueName
  The name of the queue to retrieve
  @return
  The retrieved queue with name <code>queueName</code>
  
  @throws IllegalArgumentException if there is queue with the name <code>queueName</code>