roll 3

* custom ShardingMessageExtractor can be removed

akka-sample-sharding-typed-scala/src/main/scala/sample/sharding/Device.scala

@@ -3,9 +3,6 @@ package sample.sharding
 import akka.actor.typed.ActorSystem
 import akka.actor.typed.Behavior
 import akka.actor.typed.scaladsl.Behaviors
-import akka.cluster.sharding.typed.HashCodeMessageExtractor
-import akka.cluster.sharding.typed.ShardingEnvelope
-import akka.cluster.sharding.typed.ShardingMessageExtractor
 import akka.cluster.sharding.typed.scaladsl.ClusterSharding
 import akka.cluster.sharding.typed.scaladsl.Entity
 import akka.cluster.sharding.typed.scaladsl.EntityTypeKey
@@ -20,47 +17,11 @@ object Device {
 
   def init(system: ActorSystem[_]): Unit = {
 
-    val messageExtractor =
-      new ShardingMessageExtractor[Any, Device.RecordTemperature] {
-
-        // Note that `HashCodeMessageExtractor` is using
-        // `(math.abs(id.hashCode) % numberOfShards).toString`.
-        // If the old Untyped nodes were using a different hashing function
-        // this delegate HashCodeMessageExtractor can't be used and
-        // same hashing function as before must be implemented here.
-        // `akka.cluster.sharding.typed.HashCodeMessageExtractor` is compatible
-        // with `akka.cluster.sharding.ShardRegion.HashCodeMessageExtractor`.
-        val delegate = new HashCodeMessageExtractor[Device.RecordTemperature](
-          system.settings.config
-            .getInt("akka.cluster.sharding.number-of-shards")
-        )
-
-        override def entityId(message: Any): String = {
-          message match {
-            case Device.RecordTemperature(deviceId, _) =>
-              deviceId.toString
-            case env: ShardingEnvelope[Device.RecordTemperature] =>
-              delegate.entityId(env)
-          }
-        }
-
-        override def shardId(entityId: String): String = {
-          delegate.shardId(entityId)
-        }
-
-        override def unwrapMessage(message: Any): RecordTemperature = {
-          message match {
-            case m: Device.RecordTemperature => m
-            case env: ShardingEnvelope[Device.RecordTemperature] =>
-              delegate.unwrapMessage(env)
-          }
-        }
-      }
-
-    ClusterSharding(system).init(
-      Entity(TypeKey, _ => Device())
-        .withMessageExtractor(messageExtractor)
-    )
+    // If the original hashing function was using
+    // `(math.abs(id.hashCode) % numberOfShards).toString`
+    // the default HashCodeMessageExtractor in Typed can be used.
+    // That is also compatible with `akka.cluster.sharding.ShardRegion.HashCodeMessageExtractor`.
+    ClusterSharding(system).init(Entity(TypeKey, _ => Device()))
   }
 
   case class RecordTemperature(deviceId: Int, temperature: Double)