You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: api_op_StartOnDemandAppReplication.go
    path of file: ./repos/aws-sdk-go-v2/service/sms
    
    the code of the file until where you have to start completion: // Code generated by smithy-go-codegen DO NOT EDIT.

package sms

import (
	"context"
	"fmt"
	awsmiddleware "github.com/aws/aws-sdk-go-v2/aws/middleware"
	"github.com/aws/smithy-go/middleware"
	smithyhttp "github.com/aws/smithy-go/transport/http"
)

// Starts an on-demand replication run for the specified application.
func (c *Client) StartOnDemandAppReplication(ctx context.Context, params *StartOnDemandAppReplicationInput, optFns ...func(*Options)) (*StartOnDemandAppReplicationOutput, error) {
	if params == nil {
		params = &StartOnDemandAppReplicationInput{}
	}

	result, metadata, err := c.invokeOperation(ctx, "StartOnDemandAppReplication", params, optFns, c.addOperationStartOnDemandAppReplicationMiddlewares)
	if err != nil {
		return nil, err
	}

	out := result.(*StartOnDemandAppReplicationOutput)
	out.ResultMetadata = metadata
	return out, nil
}

type StartOnDemandAppReplicationInput struct {

	// The ID of the application.
	//
	// This member is required.
	AppId *string

	// The description of the replication run.
	Description *string

	noSmithyDocumentSerde
}

type StartOnDemandAppReplicationOutput struct {
	// Metadata pertaining to the operation's resul
    
func (c *Client) addOperationStartOnDemandAppReplicationMiddlewares(stack *middleware.Stack, options Options) (err error) {
	if err := stack.Serialize.Add(&setOperationInputMiddleware{}, middleware.After); err != nil {
		return err
	}
	err = stack.Serialize.Add(&awsAwsjson11_serializeOpStartOnDemandAppReplication{}, middleware.After)
	if err != nil {
		return err
	}
	err = stack.Deserialize.Add(&awsAwsjson11_deserializeOpStartOnDemandAppReplication{}, middleware.After)
	if err != nil {
		return err
	}
	if err := addProtocolFinalizerMiddlewares(stack, options, "StartOnDemandAppReplication"); err != nil {
		return fmt.Errorf("add protocol finalizers: %v", err)
	}

	if err = addlegacyEndpointContextSetter(stack, options); err != nil {
		return err
	}
	if err = addSetLoggerMiddleware(stack, options); err != nil {
		return err
	}
	if err = addClientRequestID(stack); err != nil {
		return err
	}
	if err = addComputeContentLength(stack); err != nil {
		return err
	}
	if err = addResolveEndpointMiddleware(stack, options); err != nil {
		return err
	}
	if err = addComputePayloadSHA256(stack); err != nil {
		return err
	}
	if err = addRetry(stack, options); err != nil {
		return err
	}
	if err = addRawResponseToMetadata(stack); err != nil {
		return err
	}
	if err = addRecordResponseTiming(stack); err != nil {
		return err
	}
	if err = addClientUserAgent(stack, options); err != nil {
		return err
	}
	if err = smithyhttp.AddErrorCloseResponseBodyMiddleware(stack); err != nil {
		return err
	}
	if err = smithyhttp.AddCloseResponseBodyMiddleware(stack); err != nil {
		return err
	}
	if err = addSetLegacyContextSigningOptionsMiddleware(stack); err != nil {
		return err
	}
	if err = addOpStartOnDemandAppReplicationValidationMiddleware(stack); err != nil {
		return err
	}
	if err = stack.Initialize.Add(newServiceMetadataMiddleware_opStartOnDemandAppReplication(options.Region), middleware.Before); err != nil {
		return err
	}
	if err = addRecursionDetection(stack); err != nil {
		return err
	}
	if err = addRequestIDRetrieverMiddleware(stack); err != nil {
		return err
	}
	if err = addResponseErrorMiddleware(stack); err != nil {
		return err
	}
	if err = addRequestResponseLogging(stack, options); err != nil {
		return err
	}
	if err = addDisableHTTPSMiddleware(stack, options); err != nil {
		return err
	}
	return nil
}