@SdkInternalApi
    final EventSubscription executeAddSourceIdentifierToSubscription(AddSourceIdentifierToSubscriptionRequest addSourceIdentifierToSubscriptionRequest) {

        ExecutionContext executionContext = createExecutionContext(addSourceIdentifierToSubscriptionRequest);
        AWSRequestMetrics awsRequestMetrics = executionContext.getAwsRequestMetrics();
        awsRequestMetrics.startEvent(Field.ClientExecuteTime);
        Request<AddSourceIdentifierToSubscriptionRequest> request = null;
        Response<EventSubscription> response = null;

        try {
            awsRequestMetrics.startEvent(Field.RequestMarshallTime);
            try {
                request = new AddSourceIdentifierToSubscriptionRequestMarshaller().marshall(super.beforeMarshalling(addSourceIdentifierToSubscriptionRequest));
                // Binds the request metrics to the current request.
                request.setAWSRequestMetrics(awsRequestMetrics);
                request.addHandlerContext(HandlerContextKey.CLIENT_ENDPOINT, endpoint);
                request.addHandlerContext(HandlerContextKey.ENDPOINT_OVERRIDDEN, isEndpointOverridden());
                request.addHandlerContext(HandlerContextKey.SIGNING_REGION, getSigningRegion());
                request.addHandlerContext(HandlerContextKey.SERVICE_ID, "RDS");
                request.addHandlerContext(HandlerContextKey.OPERATION_NAME, "AddSourceIdentifierToSubscription");
                request.addHandlerContext(HandlerContextKey.ADVANCED_CONFIG, advancedConfig);

            } finally {
                awsRequestMetrics.endEvent(Field.RequestMarshallTime);
            }

            StaxResponseHandler<EventSubscription> responseHandler = new StaxResponseHandler<EventSubscription>(new EventSubscriptionStaxUnmarshaller());

            response = invoke(request, responseHandler, executionContext);

            return response.getAwsResponse();

        } finally {

            endClientExecution(awsRequestMetrics, request, response);
        }
    }
<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