Why dont use DefaultTransport?

[FarmerChillax]

I wanna support for open-telemetry in my application. like #648

I want to unify the changes, tried: http.DefaultTransport = otelhttp.NewTransport(http.DefaultTransport). but not work.
because resty does not use http.DefaultTransport, so why dont use defaultTransport?

The createTransport function is not much different from theDefaultTransport.

ref:

1. resty/client.go

   Line 1449 in 1e19d6b

   func createClient(hc *http.Client) *Client {

2. resty/transport.go

   Line 17 in 1e19d6b

   func createTransport(localAddr net.Addr) *http.Transport {