[SharePoint, Site Pages] Add parent library ID to parentReferences member

Context

When working with SharePoint lists and items different IDs are needed by different APIs. Site ID, Web ID, Item ID, Item Unique ID, relative URL etc.

There is the extreme convenient sharepointIds member that gets populated for some endpoints. But not for pages (beta API).

Observed behavior

The parentReference property of site pages only contains the siteId.

Example:

GET /beta/sites/6bbd66bf-79e9-4d81-a6a4-979be127794d/pages?$select=parentReference

Expected behavior

The parentReference property of site pages should contain the ID of the parent Site Pages library as well, if requested.

Ideal would be if the sharepointIds property of the parentReference would be populated:

For sites this is populated like so:

This shouldn't be returned by default, but upon request.

(I tried this, but get a 400: https://graph.microsoft.com/beta/sites/6bbd66bf-79e9-4d81-a6a4-979be127794d/pages?$select=parentReference,parentReference/sharepointIds. I also tried this, for single pages, as it works for sites, but does not: https://graph.microsoft.com/beta/sites/6bbd66bf-79e9-4d81-a6a4-979be127794d/pages/af4fca6a-6371-4a77-b1fb-e32c97cd7ba5/sharepointIds)

The issue names no repository files or tests; begin by locating the SharePoint Site Pages metadata definition for the parentReference member. Compare its behavior with the supplied Graph requests, and consider it done when the parent Site Pages library ID can be requested without being returned by default.