2011 Buick LaCrosse Question: Has anyone had battery positive terminal crrosion problems?

Difficult starting resulted in a check of the battery termeinals and the positive terminal of the 2011 LaCrosse was VERY badly corroded, eating into the clamp and some piece of metal plate that is under the clamp. I thought maybe there was a leak in the battery case near the post, but didn't see any cracks.
Strange battery cabling set up, with junction box on top of the battery. I guess the designer never has changed a battery in a car.
Anyone else with a similar problem? design fault?