Issue Summary

This particular bug affects subtasks in Jira Cloud, more specifically, certain subtasks are registered in the database without the "subtask_parent_id" defined.

This affects the usability of partner apps, that perform the Get issue API request: "/rest/api/3/issue/KEY" defined in the documentation: https://developer.atlassian.com/cloud/jira/platform/rest/v3/api-group-issues/#api-rest-api-3-issue-issueidorkey-get.

Steps to Reproduce

1. Locate an existing subtask with no associated "subtask_parent_id" defined in the database, or create one.
2. Perform the "/rest/api/3/issue/KEY" API request

An existing subtask information with this behavior is available in the comments which could be checked in the database. (Atlassian Internal)

Expected Results

Shows the correct "parent_id" of the subtask.

Actual Results

Does not return the value for "parent_id".

Workaround

Make Jira handle the bug gracefully by adding an exception, or adding a db constraint to make sure the "parent id" is populated (db constraint needs to be evaluated if it would have implications and should be discussed).