=str,htp clean up build warnings

- explicitly provide Unit values and place parens around tuple creation
- remove structural type usage in TestUtils
- fix Java double-casts
- use unused Java values by asserting their non-nullness
- work around inability to place case class in trait (scripted test)

The remaining warnings about using private types in public methods are
bogus as reported in https://issues.scala-lang.org/browse/SI-9490.

akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/RejectionHandlerExamplesSpec.scala

@@ -23,13 +23,13 @@ object MyRejectionHandler {
         complete(HttpResponse(BadRequest, entity = "No cookies, no service!!!"))
       }
       .handle { case AuthorizationFailedRejection ⇒
-        complete(Forbidden, "You're out of your depth!")
+        complete((Forbidden, "You're out of your depth!"))
       }
       .handleAll[MethodRejection] { methodRejections ⇒
         val names = methodRejections.map(_.supported.name)
-        complete(MethodNotAllowed, s"Can't do that! Supported: ${names mkString " or "}!")
+        complete((MethodNotAllowed, s"Can't do that! Supported: ${names mkString " or "}!"))
       }
-      .handleNotFound { complete(NotFound, "Not here!") }
+      .handleNotFound { complete((NotFound, "Not here!")) }
       .result()
 
   object MyApp extends App {

akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/DebuggingDirectivesExamplesSpec.scala

@@ -20,7 +20,7 @@ class DebuggingDirectivesExamplesSpec extends RoutingSpec {
     DebuggingDirectives.logRequest("get-user")
 
     // marks with "get-user", log with info level, HttpRequest.toString
-    DebuggingDirectives.logRequest("get-user", Logging.InfoLevel)
+    DebuggingDirectives.logRequest(("get-user", Logging.InfoLevel))
 
     // logs just the request method at debug level
     def requestMethod(req: HttpRequest): String = req.method.toString
@@ -46,7 +46,7 @@ class DebuggingDirectivesExamplesSpec extends RoutingSpec {
     DebuggingDirectives.logRequestResult("get-user")
 
     // marks with "get-user", log with info level, HttpRequest.toString, HttpResponse.toString
-    DebuggingDirectives.logRequestResult("get-user", Logging.InfoLevel)
+    DebuggingDirectives.logRequestResult(("get-user", Logging.InfoLevel))
 
     // logs just the request method and response status at info level
     def requestMethodAndResponseStatusAsInfo(req: HttpRequest): Any => Option[LogEntry] = {
@@ -72,7 +72,7 @@ class DebuggingDirectivesExamplesSpec extends RoutingSpec {
     DebuggingDirectives.logResult("get-user")
 
     // marks with "get-user", log with info level, HttpResponse.toString
-    DebuggingDirectives.logResult("get-user", Logging.InfoLevel)
+    DebuggingDirectives.logResult(("get-user", Logging.InfoLevel))
 
     // logs just the response status at debug level
     def responseStatus(res: Any): String = res match {

akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/ExecutionDirectivesExamplesSpec.scala

@@ -11,7 +11,7 @@ import akka.http.scaladsl.server._
 class ExecutionDirectivesExamplesSpec extends RoutingSpec {
   "handleExceptions" in {
     val divByZeroHandler = ExceptionHandler {
-      case _: ArithmeticException => complete(StatusCodes.BadRequest, "You've got your arithmetic wrong, fool!")
+      case _: ArithmeticException => complete((StatusCodes.BadRequest, "You've got your arithmetic wrong, fool!"))
     }
     val route =
       path("divide" / IntNumber / IntNumber) { (a, b) =>
@@ -30,7 +30,7 @@ class ExecutionDirectivesExamplesSpec extends RoutingSpec {
   }
   "handleRejections" in {
     val totallyMissingHandler = RejectionHandler.newBuilder()
-      .handleNotFound { complete(StatusCodes.NotFound, "Oh man, what you are looking for is long gone.") }
+      .handleNotFound { complete((StatusCodes.NotFound, "Oh man, what you are looking for is long gone.")) }
       .result()
     val route =
       pathPrefix("handled") {

akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/FutureDirectivesExamplesSpec.scala

@@ -23,7 +23,7 @@ class FutureDirectivesExamplesSpec extends RoutingSpec {
   implicit val myExceptionHandler =
     ExceptionHandler {
       case TestException => ctx =>
-        ctx.complete(InternalServerError, "Unsuccessful future!")
+        ctx.complete((InternalServerError, "Unsuccessful future!"))
     }
 
   val resourceActor = system.actorOf(Props(new Actor {
@@ -40,7 +40,7 @@ class FutureDirectivesExamplesSpec extends RoutingSpec {
       path("divide" / IntNumber / IntNumber) { (a, b) =>
         onComplete(divide(a, b)) {
           case Success(value) => complete(s"The result was $value")
-          case Failure(ex)    => complete(InternalServerError, s"An error occurred: ${ex.getMessage}")
+          case Failure(ex)    => complete((InternalServerError, s"An error occurred: ${ex.getMessage}"))
         }
       }
 

akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/PathDirectivesExamplesSpec.scala

@@ -16,7 +16,7 @@ class PathDirectivesExamplesSpec extends RoutingSpec {
 
   //# path-dsl
   // matches /foo/
-  path("foo" /)
+  path("foo"./)
 
   // matches e.g. /foo/123 and extracts "123" as a String
   path("foo" / """\d+""".r)

akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/RouteDirectivesExamplesSpec.scala

@@ -16,7 +16,7 @@ class RouteDirectivesExamplesSpec extends RoutingSpec {
         complete(HttpResponse(entity = "foo"))
       } ~
         path("b") {
-          complete(StatusCodes.Created, "bar")
+          complete((StatusCodes.Created, "bar"))
         } ~
         (path("c") & complete("baz")) // `&` also works with `complete` as the 2nd argument
 

akka-docs-dev/rst/scala/code/docs/stream/FlowDocSpec.scala

@@ -199,7 +199,7 @@ class FlowDocSpec extends AkkaSpec {
     val (promise, cancellable, future) = r11.run()
 
     // Type inference works as expected
-    promise.success(0)
+    promise.success(())
     cancellable.cancel()
     future.map(_ + 3)
 

akka-docs-dev/rst/scala/code/docs/stream/FlowGraphDocSpec.scala

@@ -141,8 +141,9 @@ class FlowGraphDocSpec extends AkkaSpec {
         outlets: immutable.Seq[Outlet[_]]) = {
         assert(inlets.size == this.inlets.size)
         assert(outlets.size == this.outlets.size)
-        // This is why order matters when overriding inlets and outlets
-        PriorityWorkerPoolShape(inlets(0), inlets(1), outlets(0))
+        // This is why order matters when overriding inlets and outlets.
+        // The "[Nothing, Any]" is equivalent to casting the Inlets/Outlets.
+        PriorityWorkerPoolShape[Nothing, Any](inlets(0), inlets(1), outlets(0))
       }
     }
     //#flow-graph-components-shape

akka-docs-dev/rst/scala/code/docs/stream/io/StreamFileDocSpec.scala

@@ -32,6 +32,7 @@ class StreamFileDocSpec extends AkkaSpec(UnboundedMailboxConfig) {
     //#file-source
     import akka.stream.io._
     //#file-source
+    Thread.sleep(0) // needs a statement here for valid syntax and to avoid "unused" warnings
   }
 
   {