This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
The Struts Documentation says that the package element's extends attribute can contain "one or more previous packages", though I would put money on the hibernate-default package already extending struts-default. If I could find it. I downloaded the tutorial source and no luck.
Did you notice you have a double-quote out of place in your declaration?