I look that the signature of umbraco.content.AfterUpdateDocumentCache event uses umbraco.cms.businesslogic.web.Document object. Unfortunatelly it is deprecated in "Umbraco 7".
What is the new event?
I'm the same issue in umbraco.content.AfterClearDocumentCache event.
Thanks
http://issues.umbraco.org/issue/U4-3462
According to this thread, answered by members of the Umbraco team, the AfterUpdateDocumentCache should still be used and the deprecated parameters are safely ignorable