Hello,
based on this site - https://developer.atlassian.com/cloud/jira/platform/deprecation-notice-user-privacy-api-migration-guide/#webhooks
Valid values:
atlassian: A regular Atlassian user account.app: A system account used for Connect applications and OAuth 2.0 to represent external systems.customer: A Jira Service Desk account representing an external service desk
Cheers
Adam Labus