Android Dex issue: "trouble processing "javax/transaction/HeuristicCommitException.class":

Question

Suddenly having some trouble building my app in Eclipse now. This began after updating to latest Google Client Libs. I get the error below. There are several other similar posts on SO, however none of those solutions have worked for me. I have tried checking dependencies, removing all dependencies and doing 'fix project properties', clean and rebuild.
Any ideas???

Dx 
trouble processing "javax/transaction/HeuristicCommitException.class":

Ill-advised or mistaken usage of a core class (java.* or javax.*)
when not building a core library.

This is often due to inadvertently including a core library file
in your application's project, when using an IDE (such as
Eclipse). If you are sure you're not intentionally defining a
core class, then this is the most likely explanation of what's
going on.

Answer 1

This turned out to be some jars that were accidentally placed in the source folder. Once I removed them everything worked fine.