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I'm still not able to reproduce a simple operation of writing / reading variables. I'm able to read from the workItem and display it in the form, but I'm finding really difficult to update workItem variables with form data. I followed the examples making the changes I needed, tryed to tweak some JDOM code and in the Yawl editor. I can't see the problem.
I've attached the signaled error and my code.

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My Spec file