Defined in github.com/aws/aws-sdk-go/service/rds/api.go
The type of source that will be generating the events. For example, if you want to be notified of events generated by a DB instance, you would set this parameter to db-instance. if this value is not specified, all events are returned.
Valid values: db-instance | db-cluster | db-parameter-group | db-security-group | db-snapshot | db-cluster-snapshot