NullPointerException from XWikiDocument.equals if document contains null object

While cycling through all documents in XE and looking for differences between my loader and the default, I found an error from documents which have missing places in the set of objects. XWikiDocument.equals checks to see if the other document has null objects, but doesn't check to see if "this" document has null objects before calling equals on the objects. This can cause a NullPointerException.