The HQL Validator avoids that an issue is created via the JIRA Jira 'Create' button if an HQL Action button is able to create issues in the selected Project/Issue Type
It implies that these users will be able to create an issue via the JIRA the Jira 'Create' button too.
Consequently, It's recommended to apply as Partnership Destination Credential an HQL system user.
Navigate to the Workflow associated to the Project/Issue Type for whom you want avoid issue creation via the JIRA Jira Create button
Edit the Workflow
Select the Create worrkflow transition
Click Add Validator
Select the Issue Creation Validator (HQL) and Add it
Publish the draft workflow
The HQL Validator has not effect on any Workflow transition other then the Create transion.
Login as an user that is not the user applied as Partnership destination credential.
Click the JIRAJira Create button the Destination Project and Issue Type applied on the Approval Mapping.