AlertRule API: does it also return Message Header Rules (Referenced ICOs and Iflows)?

I would like to retrieve the Message Header Rules via the AlertRule WebService API:

But it seems as SAP has forgotten this object in the API.

The API offers the following operations:

But none of them returns the Message Header Rules.

I can get all other objects of the Alert Rule but not this one. Query doesn't return the Message Header Rules.

Did I miss something?

Thanks,

Klaus