Reproducer: Span operation name duplicated when more than 1 endpoint defined per route

[seglo]

I'm using sbt-guardrail to generate akka-http Routes from an OpenAPI spec. I'm instrumenting these endpoints with Kamon's akka-http integration. I noticed that the way sbt-guardrail generates the akka-http Route sometimes causes an issue with how operation names are generated for spans. Guardrail will define Routes by their path and then define the HTTP verb as a nested Directive. This appears to cause confusion with how paths are matched in the akka-http/Kamon akka-http server instrumentation code.

i.e.)

val route = 
      path("some_endpoint") {
        post(complete(OK))
      } ~
      path("some_endpoint") {
        get(complete(OK))
      }

Reproducer test fails with:

[info] AkkaHttpServerTracingSpec:
[info] the Akka HTTP server instrumentation with HTTP/1
[info] - should return the correct operation name with overloaded route *** FAILED ***
[info]   "/some_endpoint[/some_endpoint]" was not equal to "/some_endpoint[]" (AkkaHttpServerTracingSpec.scala:89)

[ivantopo]

Hey @seglo, thanks a lot for this reproducer 🙏

I managed to fix the issue and pushed the changes (along with squashing your 2 commits) into this PR. Hopefully that will be it. I'll get back to this later today/tomorrow and merge 😄

[seglo]

Excellent. TYVM @ivantopo!