[semicolon_storm]

Not sure about that. A hash function suitable for security sensitive work, used properly, should make a collision so unlikely that you can basically forget it that it's even possible.

Think about it, that's what hashing passwords relies on. We don't store a plaintext password for a final check if the password hash matches, we count on a collision being basically impossible.

A hashmap is different, because it's using a much weaker hash function with far fewer security guarantees.

Plus, you're assuming the original values are even kept around for comparison. The cache key likely just mapped to something simple like a boolean or status flag.