If the property file is read in from /etc/xwiki/xwiki.properties then list valued properties, which are given as a CSV are not split into list elements. This mostly affects attachment.download.whitelist (if used).
Steps to reproduce:
- copy the xwiki.properties to /etc/xwiki (if this file does not already exists)
- uncomment the attachment.download.whitelist property and add application/pdf to the list of mime-types
- restart some XWiki instance and upload a PDF file with a user without programming rights
- download the PDF file; if the configuration works, you should be able to see it inline in the browser. Instead a download dialog appears.
As mostly installations from Debian packages might be affected, there is the following workaround:
- rename the /etc/xwiki/xwiki.preferences to something else
- change the symbolic link in /usr/lib/xwiki/WEB-INF/xwiki.properties to point to the renamed file.
Of course this is not update safe; one need to change the symbolic link after each update.