Putting the ! there actually makes sense with the wording in the logic, because the else statement has the var googleRowNumber, and the row number is indeed a google row, not a TMS row.

gistfile1.java

if (!isTMSstructure) {
    imgName = imageFile.getName();
} else {
    int zoom = Integer.parseInt(resultZoomDirectory.getName());
    int googleRowNumber = Integer.parseInt(FileUtils.getFileNameWithoutExtension(imageFile.getName()));
    imgName = String.valueOf(
            (int) (Math.pow(2, zoom) - 1 - googleRowNumber)) + "." + FileUtils.getFileExtension(imageFile.getName());
}

TiledRaster.java