well, it makes the end result cleaner but, what I have found is that the fact that the keys does not exists in the object, I need to do checks anyhow on the JS side so, whether I check to determine whether the key exists or check whether the array length is greater than 0, is not much different.

In fact, thinking about it as I type, having the empty arrays, might just make for less code in the end, hmmmmm.