Fingerprint of this per-instance config. This field can be used in
optimistic locking. It is ignored when inserting a per-instance config. An
up-to-date fingerprint must be provided in order to update an existing
per-instance config or the field needs to be unset.
The name of a per-instance config and its corresponding instance. Serves
as a merge key during UpdatePerInstanceConfigs operations, that is, if a
per-instance config with the same name exists then it will be updated,
otherwise a new one will be created for the VM instance with the same
name. An attempt to create a per-instance config for a VM instance that
either doesn't exist or is not part of the group will result in an error.