In net.minecraft.server.Block, void fireExtinguished(World, BlockPosition) is a CraftBukkit-added method used to trigger a BlockFadeEvent. It's called from a few places, one of them void a(World, BlockPosition, int, Random, int). This method seems to be involved in a block being destroyed by fire. If the block burn isn't cancelled and we follow the else path, we then try calling fireExtinguished on whatever the combustible block is. I'm seeing BlockFadeEvents being called on wood blocks which doesn't make any sense. Presumably it should be called on the fire, not the fuel.