IDP-1416 we discussed upgradable versus non upgradable configurations. The idea beuing the V2 is not upgradable but V3 (including V3 upgraded from V2, modulo it being warning free) is.
In V2 we played tricks with files existing or not (in V2 there was relying-party.xml but no idp.properties
It feels like it would be nice to formalize this, but I'm not sure how. I'm loth to use a property file but that might be the best solution...