How to post Json (string) value in rest adapter

Summary

I have a JSON Payload generated by javascript. how to POST this value in rest adapter

Content

I have a JSON Payload generated by javascript. how to POST this value in rest adapter

below is the sample data

{"IntegrationEntities":{"integrationEntity":[{"integrationEntityHeader":{"integrationTrackingNumber":"TrackingNum","referenceCodeForEntity":"sample","additionalInfo":"IN_PROCESS"},"integrationEntityDetails":{"requisitionApproval":{"id":"id","externalId":"externalId","approvalAction":"externalId","approvalComments":"externalId"}}}]}}

thanks in advance