Add serializer for akka.NotUsed (#24599) (#24600)

akka-docs/src/main/paradox/serialization.md

@@ -55,6 +55,7 @@ You can enable them one by one adding by adding their bindings to the misc seria
 ```
 akka.actor.serialization-bindings {
     "akka.Done"                 = akka-misc
+    "akka.NotUsed"              = akka-misc
     "akka.actor.Address"        = akka-misc
     "akka.remote.UniqueAddress" = akka-misc
 }

akka-remote/src/main/resources/reference.conf

@@ -52,9 +52,10 @@ akka {
 
 
       # The following are handled by the MiscMessageSerializer, but they are not enabled for
-      # compatibility reasons (it was added in Akka 2.5.[8,9]). Enable them by adding:
+      # compatibility reasons (it was added in Akka 2.5.[8,9,12]). Enable them by adding:
       # akka.actor.serialization-bindings {
       #   "akka.Done"                 = akka-misc
+      #   "akka.NotUsed"              = akka-misc
       #   "akka.actor.Address"        = akka-misc
       #   "akka.remote.UniqueAddress" = akka-misc
       # }
@@ -129,6 +130,7 @@ akka {
     # Additional serialization bindings which are enabled automatically when allow-java-serialization is disabled.
     java-serialization-disabled-additional-serialization-bindings = {
       "akka.Done"                 = akka-misc
+      "akka.NotUsed"              = akka-misc
       "akka.actor.Address"        = akka-misc
       "akka.remote.UniqueAddress" = akka-misc
     }

akka-remote/src/main/scala/akka/remote/serialization/MiscMessageSerializer.scala

@@ -8,7 +8,7 @@ import java.nio.charset.StandardCharsets
 import java.util.Optional
 import java.util.concurrent.TimeUnit
 
-import akka.Done
+import akka.{ Done, NotUsed }
 import akka.actor._
 import akka.dispatch.Dispatchers
 import akka.remote.WireFormats.AddressData
@@ -46,6 +46,7 @@ class MiscMessageSerializer(val system: ExtendedActorSystem) extends SerializerW
     case Kill                                 ⇒ ParameterlessSerializedMessage
     case RemoteWatcher.Heartbeat              ⇒ ParameterlessSerializedMessage
     case Done                                 ⇒ ParameterlessSerializedMessage
+    case NotUsed                              ⇒ ParameterlessSerializedMessage
     case hbrsp: RemoteWatcher.HeartbeatRsp    ⇒ serializeHeartbeatRsp(hbrsp)
     case rs: RemoteScope                      ⇒ serializeRemoteScope(rs)
     case LocalScope                           ⇒ ParameterlessSerializedMessage
@@ -288,6 +289,7 @@ class MiscMessageSerializer(val system: ExtendedActorSystem) extends SerializerW
   private val KillManifest = "K"
   private val RemoteWatcherHBManifest = "RWHB"
   private val DoneManifest = "DONE"
+  private val NotUsedManifest = "NU"
   private val AddressManifest = "AD"
   private val UniqueAddressManifest = "UD"
   private val RemoteWatcherHBRespManifest = "RWHR"
@@ -319,6 +321,7 @@ class MiscMessageSerializer(val system: ExtendedActorSystem) extends SerializerW
     KillManifest → ((_) ⇒ Kill),
     RemoteWatcherHBManifest → ((_) ⇒ RemoteWatcher.Heartbeat),
     DoneManifest → ((_) ⇒ Done),
+    NotUsedManifest → ((_) ⇒ NotUsed),
     AddressManifest → deserializeAddressData,
     UniqueAddressManifest → deserializeUniqueAddress,
     RemoteWatcherHBRespManifest → deserializeHeartbeatRsp,
@@ -352,6 +355,7 @@ class MiscMessageSerializer(val system: ExtendedActorSystem) extends SerializerW
       case Kill                               ⇒ KillManifest
       case RemoteWatcher.Heartbeat            ⇒ RemoteWatcherHBManifest
       case Done                               ⇒ DoneManifest
+      case NotUsed                            ⇒ NotUsedManifest
       case _: Address                         ⇒ AddressManifest
       case _: UniqueAddress                   ⇒ UniqueAddressManifest
       case _: RemoteWatcher.HeartbeatRsp      ⇒ RemoteWatcherHBRespManifest

akka-remote/src/test/scala/akka/remote/serialization/MiscMessageSerializerSpec.scala

@@ -5,7 +5,7 @@
 package akka.remote.serialization
 
 import akka.actor._
-import akka.remote.{ RemoteScope, RemoteWatcher, UniqueAddress }
+import akka.remote.{ RemoteScope, RemoteWatcher }
 import akka.serialization.SerializationExtension
 import akka.testkit.AkkaSpec
 import com.typesafe.config.ConfigFactory
@@ -15,8 +15,7 @@ import scala.concurrent.duration._
 import java.util.Optional
 import java.io.NotSerializableException
 
-import akka.Done
+import akka.{ Done, NotUsed }
-import akka.remote.ArteryControlFormats.UniqueAddress
 import akka.remote.routing.RemoteRouterConfig
 import akka.routing._
 
@@ -88,6 +87,7 @@ class MiscMessageSerializerSpec extends AkkaSpec(MiscMessageSerializerSpec.testC
       "RemoteWatcher.Heartbeat" → RemoteWatcher.Heartbeat,
       "RemoteWatcher.HertbeatRsp" → RemoteWatcher.HeartbeatRsp(65537),
       "Done" → Done,
+      "NotUsed" → NotUsed,
       "Address" → Address("akka", "system", "host", 1337),
       "UniqueAddress" → akka.remote.UniqueAddress(Address("akka", "system", "host", 1337), 82751),
       "LocalScope" → LocalScope,