Webhook API Verification in Azure Function

I am trying to add security to our webhook call but I can't figure out what I need for the body of the request. The example talks about a middleware to get rawBody but I don't have access to that. I tried using .json() but it isn't creating a valid signature.

Here are the options for getting the body of a request...

arrayBuffer() returns Promise<ArrayBuffer>
blob() returns Promise<Blob>
formData() returns Promise<FormData>
json() returns Promise<unknown>
text() returns Promise<string>



const signature = headers['x-zendesk-webhook-signature'];
const timestamp = headers['x-zendesk-webhook-signature-timestamp'];
const requestData: any =await request.json();
const validSign =isValidSignature(signature.toString(), timestamp, requestData);