Let EventHub REST api for batch event sending take "Body" as a json object instead of just a string.
The two options for batch sending right now are to use the managed client or the REST apis. The managed client lets you just slam in a bytesegment created on a buffer that holds valid json, but then you have to manually set name/value pairs in the Properties collection for any items that you want set in that collection. The REST api lets you just provide the whole UserProperties collection as a single json object, but then requires that you escape all your json to put it in the "Body" field as a string.
If I've already got the ability to produce json bytes, let me use that capability directly for both UserProperties and Body. Don't make me choose one or the other.
I don't care if the field has to actually have a different name for back compat purposes, I just don't want to have to take my existing json blobs and escape them to put them in the body, or have to take other json objects and deserialize them, then iterate over them to put them in UserProperties (which I would need to do if I used the managed EH client).