The problem is that when you base .equals and .hashcode on mutable properties you break Collections framework contract. And some types of collections stop working. So this article provides a workaround for that issue.
If you don't need collections (especially Set collection, Map collection, etc.), then you have no problem. :) If you don't make an object previously stored in a collection persistent, then you again have no problem. etc. etc. etc.
P.S. All the cases when you need this workaround and why one might need it are described at the beginning of the article.