xdg-dbus-proxy binary package in Ubuntu Mantic amd64

 xdg-dbus-proxy is a filtering proxy for D-Bus connections. It was
 originally part of the Flatpak project, but it has been broken out as
 a standalone module to facilitate using it in other contexts, for
 example in WebKit-GTK's optional bubblewrap-based sandbox.
 .
 For this proxy to be useful, restricted D-Bus clients must be denied
 access to the normal D-Bus socket (for example by using containers or
 AppArmor rules), and instead given access to the listening Unix socket
 created by the proxy (typically by bind-mounting it into a Linux
 container).

Source package