I also got caught out by that one. The config here isn't the entire job config, but only the subset of the config for that particular store -- so if we don't pass in that subset config, we'd still have to at least pass in the store name so that LevelDbKeyValueStore knows which store we're talking about. I thought it would be better to continue passing in the subset of the config instead.

Perhaps we should call the parameter `storeConfig` to prevent such confusion?