=htp #18661 effectiveUri in Java testkit

Java testkit now uses effectiveUri to behave just like the Scala testkit so that
the host header and path is joined. This allows for test calls that use just a relative
URI.

akka-docs-dev/rst/java/code/docs/http/javadsl/server/HeaderRequestValsExampleTest.java

@@ -32,7 +32,7 @@ public class HeaderRequestValsExampleTest extends JUnitRouteTest {
     final HttpRequest request =
       HttpRequest
         .GET("http://akka.io/")
-      .addHeader(Host.create("akka.io", 80));
+      .addHeader(Host.create("akka.io"));
     testRoute(route).run(request).assertEntity("Host header was: akka.io");
 
     //#by-class