Order Update in bulk GraphQL

[Chakori]

Trying to update order by using GraphQL by using 

HttpRequest graphQLRequest = new HttpRequest();

        graphQLRequest.setEndpoint('endpoint');

        graphQLRequest.setMethod('POST');

        graphQLRequest.setHeader('content-type', 'application/json');

        graphQLRequest.setHeader('X-Shopify-Access-Token', 'password');

        http httpSource =  new Http();   

        graphQLRequest.setBody('{"query" : "mutation { orderUpdate(input: {id: \\"gid:\\/\\/shopify\\/Order\\/37454834238791\\", note: \\"test\\"}) { order{id note}}}"}');

        HttpResponse graphQLResponse = new HttpResponse();

        graphQLResponse = httpSource.send(graphQLRequest);

        graphQLResults = graphQLResponse.getBody();

The above code is working for single order update, but when tried to bulkify the code as follows:

HttpRequest graphQLRequest = new HttpRequest();

        graphQLRequest.setEndpoint('endpoint');

        graphQLRequest.setMethod('POST');

        graphQLRequest.setHeader('content-type', 'application/json');

        graphQLRequest.setHeader('X-Shopify-Access-Token', 'password');

        http httpSource =  new Http();   

        graphQLRequest.setBody('{"query" : "mutation { orderUpdate(input: [{id: \\"gid:\\/\\/shopify\\/Order\\/37454834238791\\", note: \\"test\\"}, {id: \\"gid:\\/\\/shopify\\/Order\\/37454834238234\\", note: \\"test123\\"}]) { order{id note}}}"}');

        HttpResponse graphQLResponse = new HttpResponse();

        graphQLResponse = httpSource.send(graphQLRequest);

        graphQLResults = graphQLResponse.getBody();

It is not working.

Can someone please suggest me how to do bulk update on orders by using GraphQL?