Use customer managed encryption. If specified, kms_key_name
must contain a valid Cloud KMS key.
GoogleDefaultEncryption
Use Google default encryption.
Unspecified
Unspecified. Do not use.
UseDatabaseEncryption
Use the same encryption configuration as the database. This is the
default option when
[encryption_config][google.spanner.admin.database.v1.CreateBackupEncryptionConfig] is empty.
For example, if the database is using Customer_Managed_Encryption, the
backup will be using the same Cloud KMS key as the database.