docs: public MessagePacker packBinaryHeader(int len)
              throws IOException
      {
          if (len < (1 << 8)) {
              writeByteAndByte(BIN8, (byte) len);
          }
          else if (len < (1 << 16)) {
              writeByteAndShort(BIN16, (short) len);
          }
          else {
              writeByteAndInt(BIN32, len);
          }
          return this;
      }