Merge pull request #20055 from ktoso/wip-headers-more-fancy-ktoso

=htp #20052 headerValueByType now works with custom headers

akka-http-core/src/main/scala/akka/http/scaladsl/model/headers/headers.scala

@@ -87,6 +87,7 @@ abstract class ModeledCustomHeaderCompanion[H <: ModeledCustomHeader[H]] {
     case _               ⇒ None
   }
 
+  final implicit val implicitlyLocatableCompanion: ModeledCustomHeaderCompanion[H] = this
 }
 
 /**

akka-http-core/src/test/scala/akka/http/javadsl/HttpExtensionApiSpec.scala

@@ -380,7 +380,6 @@ class HttpExtensionApiSpec extends WordSpec with Matchers with BeforeAndAfterAll
 
     "create an outgoing connection (with 6 parameters)" in {
       val (host, port, binding) = runServer()
-      println("host = " + host)
       val flow = http.outgoingConnection(
         toHost(host, port),
         Optional.empty(),