[1.0.0-exp.8]: EntityCommandBufferSystem.Singleton and ICustomBootstrap - HOW?

[Fribur]

Got a very simple ICustomBootstrap and cannot figure out how the get the EntityCommandBufferSystem Singletons into the second world: as you can see in the picture: one world has two Singletons, and the other zero. Obviously the call to SystemAPI.GetSingleton() fails in both world as a consequence of that. Stupid mistake on my end or bug in Entities [1.0.0-exp.8]?

public class LoadingWorldBootStrap : ICustomBootstrap
{
    public bool Initialize(string defaultWorldName)
    {
        World.DefaultGameObjectInjectionWorld = new World("My Default World");
        var anotherWorld = new World("AnotherWorld");


        var systems = DefaultWorldInitialization.GetAllSystems(WorldSystemFilterFlags.Default);
        DefaultWorldInitialization.AddSystemsToRootLevelSystemGroups(World.DefaultGameObjectInjectionWorld, systems);
        ScriptBehaviourUpdateOrder.AppendWorldToCurrentPlayerLoop(World.DefaultGameObjectInjectionWorld);

        DefaultWorldInitialization.AddSystemsToRootLevelSystemGroups(anotherWorld, systems);
        ScriptBehaviourUpdateOrder.AppendWorldToCurrentPlayerLoop(anotherWorld);
        return true;
    }
}

[Fribur]

Never mind. Turns out everything was just fine and the issue above was a stupid mistake on my end after all. The following innocuous little line moved ALL entities from “anotherWorld” (which I use as a loading/staging World) to the Default World, INLCUDING the ECB singleton.

_entityManager.MoveEntitiesFrom(anotherWorldEntityManager);

Which of course leads to a duplication of the ECB Singleton in the Default world, and 0 Singletons in “anotherWorld”