Check if you can add empty sets/collections to Redis.

[PureKrome]

From this method make sure that we can add an empty collection/set to REDIS.

sample scenario:

• REDIS Get key: blah has no value.
• DB call. No result returned.
• Result is expected to be a collection of items, so the result is now an Empty Collection (e.g. db.Where()..ToArray();)
• Now we need to add this empty result to REDIS, so we avoid future db calls.

I think right now, this is erroring if adding an empty collection to REDIS.