Autocompletion on $doc is targetting XWikiDocument instead of Document

To see this issue, go to http://extensions.xwiki.org/xwiki/bin/view/Extension/AutoCompletion+Application and look at the screenshot pasted at the top.
Note that the suggested function "addAttachment()" takes an XWikiContext so it is clearly not a function of Document but rather of the internal XWikiDocument.