I'm trying to add an improvement that can be built on both land AND sea. As such, it seems I have to make two improvements. One for "DOMAIN_LAND" and the other for "DOMAIN_SEA". There is a property "SameAdjacentValid" which prevents building the same improvement next to each other, however this won't work as I need both the land and sea one to exclude each other (that is the land one should not be buildable next to the sea on and vice versa). I've tried creating a custom requirement + set that checks if there is an improvement type of the respective kinds and returning the inverse. However, I can't find a way to actually apply this requirement to the improvement. Any ideas?