Validator parameters
When adding this Validator you will be presented with a list of Validator Templates you created earlier. Choose one to add it to your Workflow.
Creating Validator Templates is very simple, yet effective and can get very powerful with multiple nested Validators and different logical operators between them. The process is practically identical to adding regular Validators offered by JIRA, so if you're familiar with JIRA workflows it should be an easy task, however you can learn more about Validator Templates here.