HTTP2 not working with SSE

package simulations

import io.gatling.core.Predef.*
import io.gatling.core.session
import io.gatling.http.Predef.*

import scala.language.postfixOps
import scala.util.Random

class ssetest extends Simulation {

  val httpProtocol = http.baseUrl("https://localhost:8443")
    .http2PriorKnowledge(Map("localhost:8443" -> true))

  val scn = scenario("ServerSentEvents")
        sse("GET messages")
          .header("MemberId", session => String.valueOf(session.userId))
            sse.checkMessage("ConnectionCheck").matching(substring("connection established"))



I am using the above code to open up SSE connections locally.

Problem Statement: HTTP/2 is not working. It always falls back to HTTP/1.1

On the other hand, if I use http.get(url) instead of sse.connect(url), it is able to establish HTTP/2 connection.

Anything I am missing here?

Indeed, Gatling’s SSE support doesn’t support HTTP/2 atm, only HTTP/1.1.

Is this something that’s critical for your organization and that you’d be willing to contribute or sponsor?