`Microsoft.Insights/Workbooks` returns `type` as null

[daddycocoaman]

Hi,

I am attempting to list resources in a subscription via the REST API and categorize things by the type field, but Microsoft.Insights/Workbooks sometimes returns null where the resource provider is usually listed for resources. This seems to be the case for all the API versions, including the newest stable 2023-06-01.

It's inconsistent and I can't determine what is causing it. Some workbooks return the type, others don't. All of these workbooks were created in 2022 and are all sourced to the same Microsoft.OperationalInsights/Workspace ID.