Encrypt swap device with a random key. This way you won't have a persistent swap device.
WARNING: Don't try to hibernate when you have at least one swap partition with this option enabled! We have no way to set the partition into which hibernation image is saved, so if your image ends up on an encrypted one you would lose it!
WARNING #2: Do not use /dev/disk/by-uuid/… or /dev/disk/by-label/… as your swap device when using randomEncryption as the UUIDs and labels will get erased on every boot when the partition is encrypted. Best to use /dev/disk/by-partuuid/…