etag property

etag is used for optimistic concurrency control as a way to help prevent simultaneous updates of a backup plan from overwriting each other.

It is strongly suggested that systems make use of the 'etag' in the read-modify-write cycle to perform BackupPlan updates in order to avoid race conditions: An etag is returned in the response to GetBackupPlan, and systems are expected to put that etag in the request to UpdateBackupPlan or DeleteBackupPlan to ensure that their change will be applied to the same version of the resource.

Output only.