Setting anchor on export in ECMA 2.0?

I've developed a call-based ECMA 2.0 XMA that exports users to a cloud service and this service authors the anchor. The DN is the users email address. I'm trying to use the seemingly proven approach of letting the XMA assign the anchor to the CS entry after the user is provisioned in the connected system, but this doesn't seem to be possible with the ECMA 2.0 spec.

The ECMA 1.0 spec seems to be able to just have cs["anchor"] = "blahblah" assigned to it, but in ECMA 2.0 there is no CSEntry, it's CSEntryChange, a sub-set of the connectors attributes that have changed.

You cannot modify the anchor attributes collection on the CSEntryChange object and adding the anchor to the CSEntryChange.AttributeChanges collection doesn't seem to have any effect.

I get the following error after export in the event log:

"Microsoft.MetadirectoryServices.ExtensibleExtensionException: The anchor attributes were not set in export entry.Forefront Identity Manager 4.0.3644.2"

The code I'm using to assign the anchor to the connector is:

var objectIdAttributeChange = AttributeChange.CreateAttributeAdd("ObjectID", objectId);
csEntryChange.AttributeChanges.Add(objectIdAttributeChange);