I believe there may be a bug in the Decision class where exception handling is concerned which causes this failure:

If the line: String transitionName = decisionHandler.decide(executionContext); ...

...in the method public void execute(ExecutionContext executionContext)

throws an exception, which is caught here in the same method:

raiseException(exception, executionContext);

We miss the block:

if (transition==null)

{ transition = getDefaultLeavingTransition(); log.debug("decision didn't select transition, taking default "+transition); }

So when executionContext.leaveNode(transition); is called at the bottom, there wil be no transition set.

I believe we need to check for a tranistion==null condition regardless of whether an excpetion has been handled. Otherwise you will never be able to handle an exception in a Decision without another unhandled exception being thrown (which kind of defeits the point