sorry - I didn't mean to indicate that using transactions to signal a roll back is an anit-pattern. I started out that comment listing good things I had see exc

sorry - I didn't mean to indicate that using transactions to signal a roll back is an anit-pattern. I started out that comment listing good things I had see exceptions used for. Then that example of the userNameInUse exception came to mind. I realize my choice of words made that less than clear.