For private uses I've rewritten the MoarOres mod. Because it was not conforming to the conventional naming scheme (e.g. it was "SteelSword" instead of "steel_sword") I renamed everything properly and process the appropriate MissingMappings events to not break old worlds, which after some troubleshooting worked fine.
Then due to the amount of changes made, I found it adequate to change the mod id from "moarores" to "moaroresreforged". It's no trouble for new worlds, but for some odd reason it seems the MissingMappings stopped working. Or rather: The MissingMappings handling *still works*, but Forge now rejects it.
The code is (the methods are called from the main class which is listening for those events)
And the output that gets produced (I reduced the listings to one block and one item each in favor of readability):
It's worth noting that the printing "Couldn't remap ..." is *not* made, so the remapping worked, but forge doesn't like it.
How can I tell forge to accept the change?