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Using a Checklist Workflow Validator, you can prevent users from successfully transitioning an issue unless all mandatory items in a checklist have been checked. An error message like the following will be displayed, and the attempted workflow transition will fail.
While you are configuring the validator parameters, select the checklist(s) to validate when determining whether to fail the transition. If you want to validate all checklists, do not select any checklists.
For Validation type, select All mandatory items checked. This tells the validator that it needs to confirm that all mandatory items are checked before allowing a transition to occur.
For Validated items, select All items. This will prompt the validator to check all the checklist items, not just the global items.