expectedRevisionId

The delete succeeds only if the named policy's current revision ID matches this value; if it differs or the policy does not exist, the operation fails with ConflictException. The "NO_POLICY" sentinel is not valid here. When omitted, deleting an absent policy is an idempotent success. Supplying this value makes the delete non-idempotent: once it succeeds the expected revision no longer exists, so retrying an unanswered request fails with ConflictException even though the policy was deleted. To establish the outcome, read the policy back: ResourceNotFoundException means the delete took effect.