Fixes codegen for multiple account ids

private/model/api/endpoint_arn.go

@@ -80,7 +80,7 @@ const accountIDWithARNShapeTmplDef = `
 		// if account id is not provided, we update the account id in modified input
 		// if account id is provided, but doesn't match with the one in ARN, we throw an error
 		// if account id is not updated, we return nil. Note that original input is not modified. 
-		func (s {{ $.ShapeName }}) updateAccountID(accountId string) (interface{}, error) {
+		func (s {{ $.ShapeName }}) update{{ $name }}(accountId string) (interface{}, error) {
 			if s.{{ $name }} == nil {
 				s.{{ $name }} = aws.String(accountId)
 				return &s, nil