I've found a way just to use the juel-imp so that the error is now gone. Now I'm trying to assign a user to a task with:
TaskService().takeTask(task.getId(), "admin");
Node:
<task candidate-users="blub" g="264,324,92,52" name="task5">
<transition g="-46,-20" name="toTask1" to="task1"/>
<transition g="-45,-20" name="toEnd1" to="end1"/>
</task>
So why is it possible to assign this node to "admin" ?
Should this not result in an error or something to determine that it didn't work ?