Fiddling with Tika in XPages

We have the annoying behaviour in an XPages application that users tend to select encrypted or password protected files from their local machine or some sort of expensive drive. The application manages the process for new products or services and when a decision has been taken for the proposal all the attached files will be combined in a single PDF file and stored in an archive. This combining process does not work well with password protected or encrypted files so either we should disallow the upload of such files or (when nobody has complained (read) about these files) they should be skipped to be combined in the final decision. But prevent uploading should be better of course (and notify the user about the file issue). So where do you start? Tika claims to be the content analysis toolkit so no looking further you would think.
This is a companion discussion topic for the original entry at https://quintessens.wordpress.com/2025/03/31/fiddling-with-tika-in-xpages/