code: static void embedTypeInfo(ErrorCorrectionLevel ecLevel, int maskPattern, ByteMatrix matrix)
        throws WriterException {
      BitArray typeInfoBits = new BitArray();
      makeTypeInfoBits(ecLevel, maskPattern, typeInfoBits);
  
      for (int i = 0; i < typeInfoBits.getSize(); ++i) {
        // Place bits in LSB to MSB order.  LSB (least significant bit) is the last value in
        // "typeInfoBits".
        boolean bit = typeInfoBits.get(typeInfoBits.getSize() - 1 - i);
  
        // Type info bits at the left top corner. See 8.9 of JISX0510:2004 (p.46).
        int[] coordinates = TYPE_INFO_COORDINATES[i];
        int x1 = coordinates[0];
        int y1 = coordinates[1];
        matrix.set(x1, y1, bit);
  
        if (i < 8) {
          // Right top corner.
          int x2 = matrix.getWidth() - i - 1;
          int y2 = 8;
          matrix.set(x2, y2, bit);
        } else {
          // Left bottom corner.
          int x2 = 8;
          int y2 = matrix.getHeight() - 7 + (i - 8);
          matrix.set(x2, y2, bit);
        }
      }
    }
docs: Embed type information. On success, modify the matrix.