false alert of `EntityCommandBuffer` in multiple jobs of one system?

The code block below seems safe to me, or am I doing something wrong?
It is throw exception on running.

Code (CSharp):

1.     public struct FooComponent : IComponentData {}
2.     public struct BarComponent : IComponentData {}
3.  
4.     public class TestSystem : SystemBase
5.     {
6.         private EndSimulationEntityCommandBufferSystem _endSimulationEntityCommandBufferSystem;
7.  
8.         protected override void OnCreate()
9.         {
10.             _endSimulationEntityCommandBufferSystem = World.GetOrCreateSystem<EndSimulationEntityCommandBufferSystem>();
11.             EntityManager.CreateEntity(typeof(FooComponent));
12.             EntityManager.CreateEntity(typeof(BarComponent));
13.             EntityManager.CreateEntity(typeof(FooComponent), typeof(BarComponent));
14.         }
15.         protected override void OnUpdate()
16.         {
17.             {
18.                 var ecb = _endSimulationEntityCommandBufferSystem.CreateCommandBuffer().ToConcurrent();
19.                 Dependency = Entities.WithAll<FooComponent>().ForEach((Entity entity) =>
20.                 {
21.                     var e = ecb;
22.                 }).ScheduleParallel(Dependency);
23.             }
24.  
25.             {
26.                 var ecb = _endSimulationEntityCommandBufferSystem.CreateCommandBuffer().ToConcurrent();
27.                 Dependency = Entities.WithAll<BarComponent>().ForEach((Entity entity) =>
28.                 {
29.                     var e = ecb;
30.                 }).ScheduleParallel(Dependency);
31.             }
32.         }
33.     }

Code (CSharp):

1. ArgumentException: The previously scheduled job TestSystem:<>c__DisplayClass_OnUpdate_LambdaJob0 writes to the UNKNOWN_OBJECT_TYPE <>c__DisplayClass_OnUpdate_LambdaJob0.JobData.ecb. You must call JobHandle.Complete() on the job TestSystem:<>c__DisplayClass_OnUpdate_LambdaJob0, before you can write to the UNKNOWN_OBJECT_TYPE safely.
2.  

 

You need to add the dependency for the ECB.

Code (CSharp):

1. _ecb.AddJobHandleForProducer(dependencies);

 

Thank you, you're right...
I used to have this line of code, and then delete it for no reason?
What a blockhead I am..