Defined in github.com/aws/aws-sdk-go/service/rds/api.go
The weekly time range during which system maintenance can occur, in Universal Coordinated Time (UTC).
Default: A 30-minute window selected at random from an 8-hour block of time per region, occurring on a random day of the week. To see the time blocks available, see Adjusting the Preferred Maintenance Window (http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/AdjustingTheMaintenanceWindow.html) in the Amazon RDS User Guide.
Valid Days: Mon, Tue, Wed, Thu, Fri, Sat, Sun
Constraints: Minimum 30-minute window.