Only EventSourcedBehavior, or nested EventSourcedBehavior allowed. exception thrown in EventSourcedBehaviorTestKit

[rameshmalla]

Description

I have a class extending EventSourcedBehavior like the following

public class Journal
    extends EventSourcedBehavior<Command, Event, State> {   
  
    private Journal(
      final String id,
      final PreRequisites preRequisites) {
    super(createPersistenceId(id));
    this.id = id;
    this.preRequisites = preRequisites;
  }

  private static PersistenceId createPersistenceId(String id) {
    return PersistenceId.of("e", id);
  }

  public static Behavior<Command> create(
      String id, ActorRef<AnotherCommand> anotherReplicatorActor) {
    return Behaviors.setup(
        context ->Behaviors.withStash(
            10,
            stash ->
                Behaviors.setup(
                    cxt -> {

                      //send message to get pre-requisites to start the journal  
                      anotherReplicatorActor.tell(
                          new GetPreRequisites(id, cxt.getSelf()));

                      return Behaviors.receive(Command.class)
                          .onMessage(
                              Command.PreRequisitesReceived.class,
                              preRequisites ->
                                  stash.unstashAll(
                                      new Journal(id, preRequisites))) //unstash all the messages and start the journal once pre-requisites are received
                          .onAnyMessage(
                              x -> {
                                stash.stash(x);
                                return Behaviors.same();
                              })
                          .build();
                    })));
   }
    
}

and I have a test that uses EventSourcedBehaviorTestKit

 import org.apache.pekko.persistence.testkit.javadsl.EventSourcedBehaviorTestKit;

ActorRef<AnotherCommand> anotherReplicatorActor = testKit.spawn(AnotherReplicator.create());
 EventSourcedBehaviorTestKit.create(
              testKit.system(),
              Journal.create(id, anotherReplicatorActor),
              new SerializationSettings(false, false, false, false, false));

when I run the test I get the below exception

Only EventSourcedBehavior, or nested EventSourcedBehavior allowed.
java.lang.IllegalArgumentException: Only EventSourcedBehavior, or nested EventSourcedBehavior allowed.
	at org.apache.pekko.persistence.testkit.internal.EventSourcedBehaviorTestKitImpl.liftedTree1$1(EventSourcedBehaviorTestKitImpl.scala:131)
	at org.apache.pekko.persistence.testkit.internal.EventSourcedBehaviorTestKitImpl.<init>(EventSourcedBehaviorTestKitImpl.scala:127)
	at org.apache.pekko.persistence.testkit.scaladsl.EventSourcedBehaviorTestKit$.apply(EventSourcedBehaviorTestKit.scala:122)
	at org.apache.pekko.persistence.testkit.javadsl.EventSourcedBehaviorTestKit$.create(EventSourcedBehaviorTestKit.scala:124)
	at org.apache.pekko.persistence.testkit.javadsl.EventSourcedBehaviorTestKit.create(EventSourcedBehaviorTestKit.scala)
	at mypackage.com.JournalEventSourcingTest.<init>(JournalEventSourcingTest.java:2)
	at java.base/jdk.internal.reflect.DirectConstructorHandleAccessor.newInstance(DirectConstructorHandleAccessor.java:62)

As I was investigating, I came across this open issue in Akka: akka/akka#30747. Could someone help me understand the underlying issues, and is there a workaround to make the tests work?

[pjfanning]

Do you want to make the change suggested in akka/akka#30747 (comment) ?