ExcelParser.open(File) uses the single argument WorkbookFactory.create() call, which opens the file in read-write mode, so when parseWorkbook() calls close on it, it will save the workbook to disk.

Usually the resulting file is the same, however it may be binary-different but equivalent(causing git conflicts). Being read-only does not cause an error since the exceptions are swallowed silently.

It should use the three argument form of WorkbookFactory.create() and pass the read-only flag