sourceImageEncryptionKey property
Thecustomer-supplied encryption key of the source image.
Required if the source image is protected by a customer-supplied encryption key.
InstanceTemplate and InstancePropertiesPatch do not storecustomer-supplied encryption keys, so you cannot create disks for instances in a managed instance group if the source images are encrypted with your own keys.
Implementation
CustomerEncryptionKey? sourceImageEncryptionKey;