int instanceId = 5;
for (Entry<String, Integer> dataDisk : spec.getDataDiskDeviceNameToSizeInGig().entrySet()) {
XMLBuilder dataDiskBuilder = sectionBuilder.e("ovf:Item");
dataDiskBuilder.e("rasd:AllocationUnits").t("Gigabytes");
dataDiskBuilder.e("rasd:Caption").t("");
dataDiskBuilder.e("rasd:Description").t("Hard Disk");
dataDiskBuilder.e("rasd:ElementName").t(dataDisk.getKey());
dataDiskBuilder.e("rasd:HostResource").t("data");
dataDiskBuilder.e("rasd:InstanceID").t("" + instanceId++);
dataDiskBuilder.e("rasd:ResourceType").t(ResourceType.PARTITIONABLE_UNIT.value());
dataDiskBuilder.e("rasd:VirtualQuantity").t(dataDisk.getValue() + "");