Hello,
Sorry, I meant JavaObject and nothing else.
#1 Using xlt/xltx template
Everything seems to work well, even upon saving. But when trying to open the file in Excel it says the file is corrupted and if I want to restore it. When restoring it almost everything seems to be correctly only some part "under the hood" is removed. The issue, at least from my point of view, is that I first open an xltx file, add data to it and then save it as xlxs file. This is doable in Excel while jPOI get confused. (Saving a template file to a new template file doesn't make any sense.) I have not yet find any additional information on the subject.
Aha! It seems that I have overlooked the option to pass a password when open the file. Great! I'll test it and come back. Thanks!