Hi @paul,
In the API response, the parent field contains issuetype, which has the hierarchyLevel property. It supports the following values: -1 for subtasks, 0 for base levels issues (Stories, Tasks etc), and 1 for epics.
So you can use parent.issuetype.hierarchyLevel to determine the type of parent.
Note that currently hierarchy levels above epic (which were previously used in Parent Link) are not yet supported by the property hierarchyLevel, so an epic’s parent will have hierarchyLevel 0. We’re currently working on enabling these hierarchies, and once it’s done, we’ll announce it separately.
Thanks,
Konstantin