Currently, the Pull Request webhook payload does not include a specific object to list the Jira issues that were linked in the commits of the Pull Request or Pull Request title. The issue key is only returned in the payload if it's part of the title of the pull request.

However, this prevents the usage of the Pull Request webhooks to trigger Jira automation( e.g automatically move a ticket to a certain state) as Jira looks specifically for an issues array in the JSON object like the below : 

{
  "issues": [
    "TEST-123",
    "TEST-124",
    "10023"
  ]
} 

This feature request is to implement a separate issues objects to be returned as part of the Pull Request webhook payload, containing all the issues that are part of the Pull Request commits/branches/title.