HTTP transport showdown

For HTTP protocol resolver currently provides following transports:

• transport-wagon that uses Maven 2.x Wagon, that among other protocols supports HTTP/1.1 as well
• transport-http that uses directly Apache HttpClient 4.x supporting HTTP/1.1 but provides enhancements in form of "checksum strategy" (almost all of remote repositories emit those in headers, sparing one HTTP round-trip)

As we saw, is very easy to outperform these as:

• Maven Central supports HTTP/1.1 but also HTTP/2
• HTTP/3 is on the way as well

An experiment involving Jetty Client far outperformed both of existing transports, most probably due HTTP/2 support.

So, clients we should consider:

• Jetty Client
• OkHTTP
• Java 11 HttpClient

Point is, to invest into something that (ideally) transparently supports HTTP/1.1 and HTTP/2, and more ideal would be if even HTTP/3 would be transparently supported (Jetty 12 works on that). We could then simply compare these implementations, count in pros and cons, and decide where we want to go,