I just submitted this bug (53043), however, I was curious if anyone has an idea for a temporary work around:
Opening and saving an XSSF workbook using ss.usermodel results in all hyperlink relations being duplicated in file/xl/worksheets/_rels/sheet.xml.rels. For example create a worksheet (excel or poi) with a single cell entry & hyperlink. This file will have a single relation entry in the location mentioned above. Open file and save file using ss.usermodel with or without making modifications. Now notice that again in the location given above there is a second hyperlink relation in the xml. This issue does not seem to affect how files are accessed, however this has become a critical issue for me as I have a file with ~5000-10000 hyperlinks that is opened and saved repeatedly. This results in all of the links being duplicated each time and it doesn't take long before the xml.rels file size exceeds several hundred Mb. This in turn seriously degrades performance. Note opening file in excel and re-saving removes all duplicate rels entries. Any suggestions would be appreciated. David
