code: @SuppressWarnings("unchecked")
    public void setExpiryFactory(Optional<Factory<? extends Expiry<K, V>>> factory) {
      expiryFactory = (Factory<Expiry<K, V>>) factory.orElse(null);
    }
docs: Set the {@link Factory} for the {@link Expiry}.
  
  @param factory the {@link Expiry} {@link Factory}