Potential memory leak due to spring-data-redis

Why does spring-data-redis stores primary key for every "hash" in a different set? For example, if we create an entity:

@RedisHash(timeToLive=10, value="event")class Event {    @Id    private String id;    ...    private String otherField;}

And then use CrudRepository<T, ID> to store objects into redis, then we could see:

1. a set named event and,
2. a hash for every object we save.

My question is, why does spring-data-redis stores all the IDs into a different set? The entries of this set are not cleared even after the ttl of a hash expires. Wouldn't this create a memory leak? Or is there a config that I'm missing?