Multi-Location Inventory Feed Submit issue

[smithburger]

Amazon is beta testing a new inventory system that is a lot like shop local. They call it Multi-Location Inventory. Our store has access and I am trying to submit a JSON inventory load sheet to update counts. To do bulk updates I need to submit the file to "/feeds/2021-06-30/documents". I think the Feed.SubmitFeed system always submits to feeds/2021-06-30/feeds? Is there a way to force SubmitFeed to /documents? Or can anyone see where I am misunderstanding their new system?

https://developer-docs.amazon.com/sp-api/docs/mli-integration-guide

I am using the example code for submitting a feed. That is working but I get a document error and I am not sure if the endpoint is the issue or the document is the issue. (Their example bulk JSON update is invalid JSON, lol)

var feedresultTXT = connection.Feed.SubmitFeed(testJsonDocument
                                        , FeedType.JSON_LISTINGS_FEED
                                        , new List<string>() { MarketPlace.US.ID }
                                        , null
                                        , ContentType.JSON);


string pathURL = string.Empty;
while (pathURL == string.Empty)
{
    Thread.Sleep(1000 * 30);
    var feedOutput = connection.Feed.GetFeed(feedresultTXT);
    if (feedOutput.ProcessingStatus == Feed.ProcessingStatusEnum.DONE)
    {
        var outPut = connection.Feed.GetFeedDocument(feedOutput.ResultFeedDocumentId);

        pathURL = outPut.Url;
    }
}