@Override
    public EventSubscription addSourceIdentifierToSubscription(AddSourceIdentifierToSubscriptionRequest request) {
        request = beforeClientExecution(request);
        return executeAddSourceIdentifierToSubscription(request);
    }
<p>
Adds a source identifier to an existing RDS event notification subscription.
</p>

@param addSourceIdentifierToSubscriptionRequest
@return Result of the AddSourceIdentifierToSubscription operation returned by the service.
@throws SubscriptionNotFoundException
        The subscription name does not exist.
@throws SourceNotFoundException
        The requested source could not be found.
@sample AmazonRDS.AddSourceIdentifierToSubscription
@see <a href="http://docs.aws.amazon.com/goto/WebAPI/rds-2014-10-31/AddSourceIdentifierToSubscription"
     target="_top">AWS API Documentation</a>
aws-java-sdk-rds/src/main/java/com/amazonaws/services/rds/AmazonRDSClient.java