API's for ISV Backup Software (Acronis BR) to carry out Agentless Backups of RHEV virtual machines...

Tricky question this, not sure where to ask. I am tld that Acronis Backup & Recovery cannot take backups of RHEV vms because the necessary API's are not available. Not sure at all if this has anything to do with REST API (which is available of course). Can anyone shed any light on this matter?