@odata.type property is missing on objects in some MS Graph endpoints

Question

(Original post: https://github.com/microsoftgraph/msgraph-beta-sdk-dotnet/issues/307)

I've noticed through the SDK and Graph Explorer (https://developer.microsoft.com/en-us/graph/graph-explorer)
that objects retrieved from the following MS Graph Beta endpoints suddenly don't have the @odata.type property anymore:

https://graph.microsoft.com/beta/Groups/
https://graph.microsoft.com/beta/devicemanagement/DeviceManagementScripts
https://graph.microsoft.com/beta/devicemanagement/GroupPolicyConfigurations
https://graph.microsoft.com/beta/devicemanagement/Intents
https://graph.microsoft.com/beta/devicemanagement/TermsAndConditions

Other MS Graph Beta endpoints that we use don't seem to suffer from this:
https://graph.microsoft.com/beta/devicemanagement/DeviceCompliancePolicies
https://graph.microsoft.com/beta/devicemanagement/DeviceEnrollmentConfigurations
https://graph.microsoft.com/beta/devicemanagement/Templates
https://graph.microsoft.com/beta/devicemanagement/WindowsAutopilotDeploymentProfiles

Clearly there's something wrong, the JSON of this MS Graph Beta endpoint does not look right:
https://graph.microsoft.com/beta/devicemanagement/DeviceConfigurations