Specifying dungeon size incorrect

[schragnasher]

Hello, I really like how you built this library and API and I wanted to use it for a fun side project. The issue I have run into is that when i specify a dungeon size.

Map<SimpleDungeonCell>? map = generator.GenerateA() .DungeonOfSize(20, 20) .ABitRandom() .SomewhatSparse() .WithMediumChanceToRemoveDeadEnds() .WithMediumSizeRooms() .WithLargeNumberOfRooms() .Now();

I actually get a dungeon of size 21,21 not 20,20. Looking at the code it seems to happen during the doubler conversion step. Can you explain to me why this steps exists and if this behavior was intended? Seems like an odd thing to do.