Disk bus number & unit number determination

Hi

Disk disk = Disk.getDiskByReference(...);
int busNumber = ...;
int unitNumber = ...;
VM vm = ...;
vm.attachDisk(disk.getReference(), busNumber, unitNumber).waitForTask(0);
Disk diskAfterAttach = Disk.getDiskByReference(...);

How is it possible to determine the bus and unit number from the diskAfterAttach?

This information is available on the vCloud GUI so this must be possible.

Thanks Denes