Values:
TYPE_UNSPECIFIED (0):
Encryption type not specified. Defaults to
GOOGLE_DEFAULT_ENCRYPTION.
GOOGLE_DEFAULT_ENCRYPTION (1):
The data is encrypted at rest with a key that
is fully managed by Google. No key version will
be populated. This is the default state.
CUSTOMER_MANAGED_ENCRYPTION (2):
The data is encrypted at rest with a key that
is managed by the customer. KMS key versions
will be populated.