code: public synchronized void write(int b) throws IOException {
      eventStartWrite();
  
      try {
        sum.update(b);
        buf[count++] = (byte) b;
        if (bytesSentInChunk + count == buf.length) {
          flushBuffer(true, shouldKeepPartialChunkData());
        }
      } finally {
        eventEndWrite();
      }
    }
docs: Write one byte