The HQL Validator allows to avoid that an issue is create via the JIRA 'Create' button if an HQL Action button exists having the selected Project/Issue Type as target Project/Issue Type.
When applying the HQL Validator, on trying to create an issue, it checks on all mappings having as target Project and Issue Type the selected ones and having the Quick Action Button/Post Function turned On in order to allow the issue creation to the users configured as Partnership Destination Credential on the associated Partnerships exclusively.
It implies that these users will be able to create an issue via the JIRA 'Create' button too.
Consequently, It's recommended to apply as Partnership Destination Credential an HQL system user.
The Allow issue creation/linking via partnership credentials must be turned On.