Use DI helper to create the processor

src/Microsoft.ApplicationInsights.AspNetCore/Extensions/ApplicationInsightsExtensions.cs

@@ -190,7 +190,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// </returns>
         public static IServiceCollection AddApplicationInsightsTelemetryProcessor<T>(this IServiceCollection services) where T : ITelemetryProcessor
         {
-            return services.AddSingleton<ITelemetryProcessorFactory>(new TelemetryProcessorFactory<T>());
+            return services.AddSingleton<ITelemetryProcessorFactory>(serviceProvider => new TelemetryProcessorFactory<T>(serviceProvider));
         }
 
         /// <summary>

src/Microsoft.ApplicationInsights.AspNetCore/Implementation/TelemetryProcessorFactory.cs

@@ -2,6 +2,7 @@
 {
     using System;
     using Microsoft.ApplicationInsights.Extensibility;
+    using Microsoft.Extensions.DependencyInjection;
 
     /// <summary>
     /// A generic factory for telemetry processors of a given type.
@@ -9,6 +10,17 @@
     /// <typeparam name="T">The type of telemetry processor created by this factory.</typeparam>
     internal class TelemetryProcessorFactory<T> : ITelemetryProcessorFactory where T : ITelemetryProcessor
     {
+        private readonly IServiceProvider serviceProvider;
+
+        /// <summary>
+        /// Constructs an instance of the factory.
+        /// </summary>
+        /// <param name="serviceProvider">The service provider.</param>
+        public TelemetryProcessorFactory(IServiceProvider serviceProvider)
+        {
+            this.serviceProvider = serviceProvider;
+        }
+
         /// <summary>
         /// Creates an instance of the telemetry processor, passing the
         /// next <see cref="ITelemetryProcessor"/> in the call chain to
@@ -16,7 +28,7 @@
         /// </summary>
         public ITelemetryProcessor Create(ITelemetryProcessor next)
         {
-            return (ITelemetryProcessor)Activator.CreateInstance(typeof(T), args: next);
+            return ActivatorUtilities.CreateInstance<T>(serviceProvider, next);
         }
     }
 }