in http/server/requestid/requestid.go [54:70]
func (m *requestIDMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
headers := m.extractor(r)
// Create metadata pairs from the extracted headers
var mdPairs []string
for key, value := range headers {
mdPairs = append(mdPairs, key, value)
}
md := metadata.Pairs(mdPairs...)
// Add headers to incoming context metadata to make them available for forwarding
ctx = metadata.NewIncomingContext(ctx, md)
m.next.ServeHTTP(w, r.WithContext(ctx))
}