It seems that using the new .Net 6 source generator base classes makes the resulting builder incompatible with VS2019. Now that VS2022 is in general availability, I don't think this is a big issue, but I wanted to leave this here for others to find. If I can find a way to make it get along with VS2019, I will, but it seems like more of a "Microsoft Problem" to me at the moment.
It seems that using the new .Net 6 source generator base classes makes the resulting builder incompatible with VS2019. Now that VS2022 is in general availability, I don't think this is a big issue, but I wanted to leave this here for others to find. If I can find a way to make it get along with VS2019, I will, but it seems like more of a "Microsoft Problem" to me at the moment.