This validator confirms whether the parent issue matches the specified JQL.
To add the Parent Issue JQL Validator
Go to the transition of your workflow, switch to the Validators tab and then click on the Add Validator button.
Select JEP - Parent Issue JQL validator and then click the Add button.
Type the JQL that the parent issue should match in order to proceed with the transition. Also type the message that should be displayed if the JQL does not match.
Click the Add button and that's it.
If the parent issue does not match the JQL defined above, then it will not proceed with the transition and will give an error message like the one below.
Do not forget to publish the workflow!