How do you use the API to import a PBIX to a group workspace?

When I publish from PowerBI Desktop, I can select the workspace.  But looking at the API, I can't see how to specify the workspace...

https://msdn.microsoft.com/en-us/library/mt243840.aspx

Note:  I notice the API for PowerBI Embedded seems to have this capability - although perhaps 'workspace' means something a bit different in Embedded.   

https://msdn.microsoft.com/en-us/library/microsoft.powerbi.api.beta.importsextensions.postimportwithfile.aspx