=htp #20884 fix header name rendering issue when $minus present (#20940)

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

@@ -21,7 +21,7 @@ import akka.http.javadsl.{ model ⇒ jm }
 import akka.http.scaladsl.model._
 
 sealed abstract class ModeledCompanion[T: ClassTag] extends Renderable {
-  val name = getClass.getSimpleName.replace("$minus", "-").dropRight(1) // trailing $
+  val name = ModeledCompanion.nameFromClass(getClass)
   val lowercaseName = name.toRootLowerCase
   private[this] val nameBytes = name.asciiBytes
   final def render[R <: Rendering](r: R): r.type = r ~~ nameBytes ~~ ':' ~~ ' '
@@ -36,6 +36,14 @@ sealed abstract class ModeledCompanion[T: ClassTag] extends Renderable {
       case res                                         ⇒ Left(res.errors)
     }
 }
+/** INTERNAL API */
+private[akka] object ModeledCompanion {
+  def nameFromClass[T](clazz: Class[T]): String = {
+    val name = clazz.getSimpleName.replace("$minus", "-")
+    if (name.last == '$') name.dropRight(1) // trailing $
+    else name
+  }
+}
 
 sealed trait ModeledHeader extends HttpHeader with Serializable {
   def renderInRequests: Boolean = false // default implementation

akka-http-tests/src/test/scala/akka/http/scaladsl/server/directives/HeaderDirectivesSpec.scala

@@ -34,7 +34,7 @@ class HeaderDirectivesSpec extends RoutingSpec with Inside {
   }
 
   "The headerValueByType directive" should {
-    lazy val route =
+    val route =
       headerValueByType[Origin]() { origin ⇒
         complete(s"The first origin was ${origin.origins.head}")
       }
@@ -51,6 +51,16 @@ class HeaderDirectivesSpec extends RoutingSpec with Inside {
         }
       }
     }
+    "reject a request for missing header, and format it properly when header included special characters (e.g. `-`)" in {
+      val route = headerValueByType[`User-Agent`]() { agent ⇒
+        complete(s"Agent: ${agent}")
+      }
+      Get("abc") ~> route ~> check {
+        inside(rejection) {
+          case MissingHeaderRejection("User-Agent") ⇒
+        }
+      }
+    }
   }
 
   "The headerValueByName directive" should {

akka-http/src/main/scala/akka/http/scaladsl/server/directives/HeaderDirectives.scala

@@ -7,7 +7,7 @@ package directives
 
 import akka.http.impl.util._
 import akka.http.scaladsl.model._
-import akka.http.scaladsl.model.headers.{ HttpOriginRange, ModeledCustomHeader, ModeledCustomHeaderCompanion, Origin }
+import akka.http.scaladsl.model.headers._
 
 import scala.reflect.ClassTag
 import scala.util.control.NonFatal
@@ -91,7 +91,7 @@ trait HeaderDirectives {
    * @group header
    */
   def headerValueByType[T](magnet: HeaderMagnet[T]): Directive1[T] =
-    headerValuePF(magnet.extractPF) | reject(MissingHeaderRejection(magnet.runtimeClass.getSimpleName))
+    headerValuePF(magnet.extractPF) | reject(MissingHeaderRejection(magnet.headerName))
 
   //#optional-header
   /**
@@ -159,6 +159,7 @@ object HeaderDirectives extends HeaderDirectives
 trait HeaderMagnet[T] {
   def classTag: ClassTag[T]
   def runtimeClass: Class[T]
+  def headerName = ModeledCompanion.nameFromClass(runtimeClass)
 
   /**
    * Returns a partial function that checks if the input value is of runtime type