The challenge will be finding out whence the Desktop Bus service definition for org.bluez.obex is installed on your operating system.
/usr/local/share/dbus-1/services or /usr/share/dbus-1/services is the starting point.
"Helpfully", the Desktop Bus service file does not have to be named anything appropriate, but just has to have Name=org.bluez.obex in the file itself.
Equally helpfully, Debian et al. have decided that *next* name that you get to look up is not dbus-org.bluez.obex.service , but Debian's own (long-standing) name for this.
https://sources.debian.org/src/bluez/5.82-1.1/debian/patches/org.bluez.obex.service.in.patch