Refactor background worker initialization to use optional cancellation token from IHostApplicationLifetime

framework/src/Volo.Abp.BackgroundWorkers/Volo/Abp/BackgroundWorkers/AbpBackgroundWorkersModule.cs

@@ -1,4 +1,5 @@
-using System.Threading.Tasks;
+using System.Threading;
+using System.Threading.Tasks;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Options;
@@ -17,10 +18,11 @@ public class AbpBackgroundWorkersModule : AbpModule
         var options = context.ServiceProvider.GetRequiredService<IOptions<AbpBackgroundWorkerOptions>>().Value;
         if (options.IsEnabled)
         {
-            var hostApplicationLifetime = context.ServiceProvider.GetRequiredService<IHostApplicationLifetime>();
+            var hostApplicationLifetime = context.ServiceProvider.GetService<IHostApplicationLifetime>();
+            var cancellationToken = hostApplicationLifetime?.ApplicationStopping ?? CancellationToken.None;
             await context.ServiceProvider
                 .GetRequiredService<IBackgroundWorkerManager>()
-                .StartAsync(hostApplicationLifetime.ApplicationStopping);
+                .StartAsync(cancellationToken);
         }
     }
 
@@ -29,10 +31,11 @@ public class AbpBackgroundWorkersModule : AbpModule
         var options = context.ServiceProvider.GetRequiredService<IOptions<AbpBackgroundWorkerOptions>>().Value;
         if (options.IsEnabled)
         {
-            var hostApplicationLifetime = context.ServiceProvider.GetRequiredService<IHostApplicationLifetime>();
+            var hostApplicationLifetime = context.ServiceProvider.GetService<IHostApplicationLifetime>();
+            var cancellationToken = hostApplicationLifetime?.ApplicationStopping ?? CancellationToken.None;
             await context.ServiceProvider
                 .GetRequiredService<IBackgroundWorkerManager>()
-                .StopAsync(hostApplicationLifetime.ApplicationStopping);
+                .StopAsync(cancellationToken);
         }
     }
 

framework/src/Volo.Abp.BackgroundWorkers/Volo/Abp/BackgroundWorkers/BackgroundWorkersApplicationInitializationContextExtensions.cs

@@ -31,8 +31,11 @@ public static class BackgroundWorkersApplicationInitializationContextExtensions
 
         if (cancellationToken == default)
         {
-            var hostApplicationLifetime = context.ServiceProvider.GetRequiredService<IHostApplicationLifetime>();
-            cancellationToken = hostApplicationLifetime.ApplicationStopping;
+            var hostApplicationLifetime = context.ServiceProvider.GetService<IHostApplicationLifetime>();
+            if (hostApplicationLifetime != null)
+            {
+                cancellationToken = hostApplicationLifetime.ApplicationStopping;
+            }
         }
 
         await context.ServiceProvider