docs: static void embedDataBits(BitArray dataBits, int maskPattern, ByteMatrix matrix)
        throws WriterException {
      int bitIndex = 0;
      int direction = -1;
      // Start from the right bottom cell.
      int x = matrix.getWidth() - 1;
      int y = matrix.getHeight() - 1;
      while (x > 0) {
        // Skip the vertical timing pattern.
        if (x == 6) {
          x -= 1;
        }
        while (y >= 0 && y < matrix.getHeight()) {
          for (int i = 0; i < 2; ++i) {
            int xx = x - i;
            // Skip the cell if it's not empty.
            if (!isEmpty(matrix.get(xx, y))) {
              continue;
            }
            boolean bit;
            if (bitIndex < dataBits.getSize()) {
              bit = dataBits.get(bitIndex);
              ++bitIndex;
            } else {
              // Padding bit. If there is no bit left, we'll fill the left cells with 0, as described
              // in 8.4.9 of JISX0510:2004 (p. 24).
              bit = false;
            }
  
            // Skip masking if mask_pattern is -1.
            if (maskPattern != -1 && MaskUtil.getDataMaskBit(maskPattern, xx, y)) {
              bit = !bit;
            }
            matrix.set(xx, y, bit);
          }
          y += direction;
        }
        direction = -direction;  // Reverse the direction.
        y += direction;
        x -= 2;  // Move to the left.
      }
      // All bits should be consumed.
      if (bitIndex != dataBits.getSize()) {
        throw new WriterException("Not all bits consumed: " + bitIndex + '/' + dataBits.getSize());
      }
    }