GNOME != Fedora

Are you referring to the format of the configuration file? The INI format, predates Java, of course, and the reverse-DNS naming convention is standard in many situations where unrelated organizations must provide unique IDs. So far as I am aware there is no Java code in any of these components.

It would have been helpful of the action names were grouped a bit better; you can use glob patterns, but the org.freedesktop.udisks.* actions are a mixture of normal user actions (e.g. "mount removable filesystem") and things which should require administrative privileges (e.g. "manage the LVM subsystem" or "lock encrypted LUKS devices unlocked by other users"). I didn't see any obvious combination of positive glob patterns which would be sure to select just the normal user actions, short of listing them all. Renaming the actions enabled by default for interactive sessions to something like org.freedesktop.udisks.safe.* would have allowed for a much more compact configuration, but I realize that has its own issues. Groups, or multiple Action= lines, would be nice. Perhaps the ability to filter actions based on a glob pattern plus the current Result* settings ("allow all udisk actions which this user could use in an active session"). Or at least some (documented) way to break values over multiple lines.

There used to be a GUI for configuring PolicyKit permissions, but apparently no one's updated it for the PolKit-1 redesign.