How to list all O365 meeting rooms?

Hello. Office 365 allows user to create meeting rooms testroom1@x.onmicrosoft.com, testroom2@x.onmicrosoft.com,testroom3@x.onmicrosoft.com  (https://portal.office.com/adminportal/home#/ResourceMailbox).  I would like to read these room in console application.

I used EWS (https://msdn.microsoft.com/en-us/library/office/dn643730%28v=exchg.150%29.aspx?f=255&MSPPError=-2147217396) to authenticate to O365 but EmailAddressCollection myrooms = Service.GetRoomLists(); does not return results.  I can use EWS to send email so connection should work. Am I doing something wrong? If so how can I list all meeting rooms / resources?