Send large numbers of inventory updates in one request.

Use this API to send very large amounts of inventory update objects (up to two gigabytes) in a single API call. The API will receive the inventory updataes and process them after the fact.  Developers may call the InventoryChangeLog API to determine what happened.  Due to the large amount of data that can be sent, the process of sending the data has two steps:

1. Call this API to authenticate which then returns the destination URL to PUT the content to and then
2. PUT content to the destination URL returned in #1 above where each ItemInventory JSON Object is sent as a JSON object followed by a new line character (see JSON Lines documentation)