I'm currently running systemd 219-78. I realize there's significant behavior differences in the current release, but per the documentation, I take it the behavior of '-clean' hasn't changed in regards to directly specifications only applying to the directory entry and the top level files. AKA, it still won't do recursive evaluation.
I also assume that the '-clean' behavior also still doesn't provide any 'glob' behavior specifications. Primary issue for my side is managing tomcat tmp files. These create a file in its temp location with a directory named of the form 'tomcat.<####>' with other associated files (or directories below this). As such, we can't use 'systemd-tmpfiles' to purge these, though it's desirable to do so. Is the current status for "system-tmpfiles" still such that the above can't be achieved with this subsystem?