code: private void sendChunkSize() {
          if (chunkSizeSent.compareAndSet(false, true)) {
              log.debug("Sending chunk size: {}", chunkSize);
              ChunkSize chunkSizeMsg = new ChunkSize(chunkSize);
              conn.getChannel((byte) 2).write(chunkSizeMsg);
          }
      }
docs: Send the chunk size