This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
I am not sure, but JtaTransactionManager is the parent class of WebsphereUowTransactionManager in Spring. Maybe because you are using something more specific to Websphere, it can't get that value anymore.