I have a task and a sub-task. I need to create a condition for that: I only proceed with a task only when all ub-tasks are completed.
Let's suppose you want to prevent a transition "T" from being executed while there exists a sub-task in a status different from "Resolved" or "Closed".
You should insert in transition "T" a Condition on sub-tasks or Validation on sub-tasks with the following configuration:
Once configured, transition "T" will look like this: