How does one Get and Set value of Work Item's Found-In attribute programmatically?

Please have a look at: https://jazz.net/wiki/bin/view/Main/ProgrammaticWorkItemCreation

You can use the operation also to update work items, this saves you trying to work with working copies.

You want to set the value of the attribute: com.ibm.team.workitem.attribute.version the data type is IDeliverables.

Some hint on IDeliverables: https://jazz.net/library/article/807 there are several ways to find them.

Forgot: To set an internal attribute:

            IWorkItemClient workItemClient= (IWorkItemClient) teamRepository.getClientLibrary(IWorkItemClient.class);
           
            IAttribute attribute = workItemClient.findAttribute(workItem.getProjectArea(),
                    fAttributeID, monitor);
            if(null!=attribute){
                if(workItem.hasAttribute(attribute))
                    workItem.setValue(attribute, fValue);
            }

To get use gatValue and cast. For custom attributes use hasCustomAttribute  which also works for built in attributes.