I tried the following experiment:
I modified my model so that a particular task was statically assigned to a certain user. This user is registered at the task server, however in my User Group Callback I modified the logic so that when that user's id is passed in, the method returns false.
My assumption being that, when the process instance arrives at this task, some sort of exception will be thrown because the callback says the user doesn't exist.
Using a breakpoint, I confirmed that the method is called and that it returns "false" in this situation. However, this didn't seem to matter. The task was still reserved for that user and the user is still able to complete it.
So I am wondering, what is the purpose of this method?
Not a show-stopper but I would just like to understand, thanks!