@SdkInternalApi
    final DescribeDBSubnetGroupsResult executeDescribeDBSubnetGroups(DescribeDBSubnetGroupsRequest describeDBSubnetGroupsRequest) {

        ExecutionContext executionContext = createExecutionContext(describeDBSubnetGroupsRequest);
        AWSRequestMetrics awsRequestMetrics = executionContext.getAwsRequestMetrics();
        awsRequestMetrics.startEvent(Field.ClientExecuteTime);
        Request<DescribeDBSubnetGroupsRequest> request = null;
        Response<DescribeDBSubnetGroupsResult> response = null;

        try {
            awsRequestMetrics.startEvent(Field.RequestMarshallTime);
            try {
                request = new DescribeDBSubnetGroupsRequestMarshaller().marshall(super.beforeMarshalling(describeDBSubnetGroupsRequest));
                // 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, "DescribeDBSubnetGroups");
                request.addHandlerContext(HandlerContextKey.ADVANCED_CONFIG, advancedConfig);

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

            StaxResponseHandler<DescribeDBSubnetGroupsResult> responseHandler = new StaxResponseHandler<DescribeDBSubnetGroupsResult>(
                    new DescribeDBSubnetGroupsResultStaxUnmarshaller());

            response = invoke(request, responseHandler, executionContext);

            return response.getAwsResponse();

        } finally {

            endClientExecution(awsRequestMetrics, request, response);
        }
    }
<p>
Returns a list of DBSubnetGroup descriptions. If a DBSubnetGroupName is specified, the list will contain only the
descriptions of the specified DBSubnetGroup.
</p>
<p>
For an overview of CIDR ranges, go to the <a
href="http://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing">Wikipedia Tutorial</a>.
</p>

@param describeDBSubnetGroupsRequest
@return Result of the DescribeDBSubnetGroups operation returned by the service.
@throws DBSubnetGroupNotFoundException
        <code>DBSubnetGroupName</code> doesn't refer to an existing DB subnet group.
@sample AmazonRDS.DescribeDBSubnetGroups
@see <a href="http://docs.aws.amazon.com/goto/WebAPI/rds-2014-10-31/DescribeDBSubnetGroups" target="_top">AWS API
     Documentation</a>
aws-java-sdk-rds/src/main/java/com/amazonaws/services/rds/AmazonRDSClient.java