code: private void resetAllQueuesOrStreams(boolean clearStreams, @Nullable String prefix) {
      List<String> toRemove = Lists.newArrayListWithCapacity(queues.size());
      for (String queueName : queues.keySet()) {
        if ((clearStreams && QueueName.isStream(queueName)) || (!clearStreams && QueueName.isQueue(queueName))) {
          if (prefix == null ||  queueName.startsWith(prefix)) {
            toRemove.add(queueName);
          }
        }
      }
      for (String queueName : toRemove) {
        queues.remove(queueName);
      }
    }
docs: Drop either all streams or all queues.
  @param clearStreams if true, drops all streams, if false, clears all queues.
  @param prefix if non-null, drops only queues with a name that begins with this prefix.