},
		config.HelpKV{
			Key:         BatchSize,
			Description: "Number of events per HTTP send to webhook target",
			Optional:    true,
			Type:        "number",
		},
		config.HelpKV{
			Key:         QueueSize,
			Description: "configure channel queue size for webhook targets",
			Optional:    true,
			Type:        "number",
		},
		config.HelpKV{
			Key:         QueueDir,

     */
    public SimplexTransferListener(
            TransferListener delegate, int queueSize, int batchMaxSize, boolean blockOnLastEvent) {
        this.delegate = requireNonNull(delegate);
        if (queueSize < 1 || batchMaxSize < 1) {
            throw new IllegalArgumentException("Queue and batch sizes must be greater than 1");
        }

   * queue. If may return a nonzero value after the web socket has been canceled; this indicates
   * that enqueued messages were not transmitted.
   */
  fun queueSize(): Long

  /**
   * Attempts to enqueue `text` to be UTF-8 encoded and sent as a the data of a text (type `0x1`)
   * message.
   *