I have two friends who both purchased Minecraft Java Edition before 2015 (I think), and therefore they would receive a free copy of Minecraft for Windows 10. They didn't know about this until recently when I told them about it, but when they went to account.mojang.com to claim the free copy it told them that it was out of codes and that they should come back later because there will be more codes available then. Of course I thought it wasn't a bug, but it's been out of codes for 3 days now.