Skip to set `CorrelationId ` if current value is `null`.

Resolve #21419

framework/src/Volo.Abp.EventBus/Volo/Abp/EventBus/Distributed/DistributedEventBusBase.cs

@@ -133,7 +133,10 @@ public abstract class DistributedEventBusBase : EventBusBase, IDistributedEventB
                     Serialize(eventData),
                     Clock.Now
                 );
-                outgoingEventInfo.SetCorrelationId(CorrelationIdProvider.Get()!);
+                if (CorrelationIdProvider.Get() != null)
+                {
+                    outgoingEventInfo.SetCorrelationId(CorrelationIdProvider.Get()!);
+                }
                 await eventOutbox.EnqueueAsync(outgoingEventInfo);
                 return true;
             }

framework/src/Volo.Abp.Http.Client/Volo/Abp/Http/Client/ClientProxying/ClientProxyBase.cs

@@ -310,7 +310,11 @@ public class ClientProxyBase<TService> : ITransientDependency
         }
 
         //CorrelationId
-        requestMessage.Headers.Add(AbpCorrelationIdOptions.Value.HttpHeaderName, CorrelationIdProvider.Get());
+        var correlationId = CorrelationIdProvider.Get();
+        if (correlationId != null)
+        {
+            requestMessage.Headers.Add(AbpCorrelationIdOptions.Value.HttpHeaderName, correlationId);
+        }
 
         //TenantId
         if (CurrentTenant.Id.HasValue)

framework/src/Volo.Abp.Http.Client/Volo/Abp/Http/Client/DynamicProxying/ApiDescriptionFinder.cs

@@ -126,7 +126,11 @@ public class ApiDescriptionFinder : IApiDescriptionFinder, ITransientDependency
     protected virtual void AddHeaders(HttpRequestMessage requestMessage)
     {
         //CorrelationId
-        requestMessage.Headers.Add(AbpCorrelationIdOptions.HttpHeaderName, CorrelationIdProvider.Get());
+        var correlationId = CorrelationIdProvider.Get();
+        if (correlationId != null)
+        {
+            requestMessage.Headers.Add(AbpCorrelationIdOptions.HttpHeaderName, correlationId);
+        }
 
         //TenantId
         if (CurrentTenant.Id.HasValue)