InvokeAsync<T> and batch handlers

[rsmithsa]

We've got a case where on startup/bootstrap of a service we are trying to re-use handlers for initialisation. We basically replay messages until we are at the "current" state - and use request/reply to ensure that all the initial work is complete. This worked well until we added batching for certain of those handlers.

We were expecting something like this to work:

// Handler
public class BatchHandler
{
    public async Task<SomeResponse> Handle(Item[] items)
    {
        return new SomeResponse();
    }
}

//Invocation elsewhere
var r = await bus.InvokeAsync<SomeResponse>(new Item(), ct);

// Or alternatively
var t = new List<Task>();
foreach (var item in items)
{
    t.Add(bus.InvokeAsync<SomeResponse>(item, ct);)
}

await Task.WhenAll(t);

This results in an exception like:

Wolverine.Runtime.RemoteInvocation.WolverineRequestReplyException: 'Request failed: No response was created for expected response 'SomeResponse'. No cascading messages were created by this handler'

I'm not sure if this is a bug or intended behaviour? I.e. Is this something that was intended to be supported?