CCPMAC

I've examined the source code of many minecraft mods and the game itself and nothing has made it any clearer on how to place a structure into a world. For this one, I look through the command class and can't tell what's doing the summoning

So how do I actually pop the structure?

I'm having trouble figuring out how to use the PlaceCommand.placeStructure() method. This is because I can't figure out what the CommandSourceStack and Holder.Reference<Structure> pStructure parameters are and how to structure them, and extensive searching on the internet left me empty handed. Anyone have any advice on how to use this method?

I wanted to know if there was a way to generate a structure other than a tree when a sapling grew, such as a villager house.