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_AssociateSourceGraphqlApi.go
    path of file: ./repos/aws-sdk-go-v2/service/appsync
    
    the code of the file until where you have to start completion: // Code generated by smithy-go-codegen DO NOT EDIT.

package appsync

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

// Creates an association between a Merged API and source API using the Merged
// API's identifier.
func (c *Client) AssociateSourceGraphqlApi(ctx context.Context, params *AssociateSourceGraphqlApiInput, optFns ...func(*Options)) (*AssociateSourceGraphqlApiOutput, error) {
	if params == nil {
		params = &AssociateSourceGraphqlApiInput{}
	}

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

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

type AssociateSourceGraphqlApiInput struct {

	// The identifier of the AppSync Merged API. This is generated by the AppSync
	// service. In most cases, Merged APIs (especially in your account) only require
	// the API ID value or ARN of the merge
    
func (c *Client) addOperationAssociateSourceGraphqlApiMiddlewares(stack *middleware.Stack, options Options) (err error) {
	if err := stack.Serialize.Add(&setOperationInputMiddleware{}, middleware.After); err != nil {
		return err
	}
	err = stack.Serialize.Add(&awsRestjson1_serializeOpAssociateSourceGraphqlApi{}, middleware.After)
	if err != nil {
		return err
	}
	err = stack.Deserialize.Add(&awsRestjson1_deserializeOpAssociateSourceGraphqlApi{}, middleware.After)
	if err != nil {
		return err
	}
	if err := addProtocolFinalizerMiddlewares(stack, options, "AssociateSourceGraphqlApi"); 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 = addOpAssociateSourceGraphqlApiValidationMiddleware(stack); err != nil {
		return err
	}
	if err = stack.Initialize.Add(newServiceMetadataMiddleware_opAssociateSourceGraphqlApi(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
}