First create a map to propagate headers and then variables to hold the header names and the header values.
prop map[string]string
headern = []string{"l5dctxtrace", "xrequestidid", "xotspancontextontext", "xb3traceid", "xb3spanid", "xb3parentspanid", "xb3sampled", "xb3flags"}
headerv = []string{"l5d-ctx-trace", "x-request-id", "x-ot-span-context", "x-b3-traceid", "x-b3-spanid", "x-b3-parentspanid", "x-b3-sampled", "x-b3-flags"}
In the function that receives the inbound HTTP request, capture the headers (passed by Envoy)