Fixed more issues

src/HotChocolate/Utilities/src/Utilities/ServiceFactory.cs

@@ -12,6 +12,11 @@ public class ServiceFactory : IServiceProvider
 
         public object? CreateInstance(Type type)
         {
+            if (type is null)
+            {
+                throw new ArgumentNullException(nameof(type));
+            }
+
             try
             {
                 return ActivatorHelper.CompileFactory(type).Invoke(Services ?? _empty);

src/HotChocolate/Utilities/test/Utilities.Tests/ActivatorHelperTests.cs

@@ -57,19 +57,6 @@ public void CreateInstanceFactory_From_AbstactClass()
                 .Message.MatchSnapshot();
         }
 
-        [Fact]
-        public void CreateInstanceFactory_From_Class_With_Multiple_Constructors()
-        {
-            // arrange
-            // act
-            Action action = () => ActivatorHelper
-                .CompileFactory(typeof(Foo).GetTypeInfo());
-
-            // assert
-            Assert.Throws<InvalidOperationException>(action)
-                .Message.MatchSnapshot();
-        }
-
         public interface IFoo
         {
 

website/src/blog/2020-07-16-version-11/2020-07-16-version-11.md

@@ -119,3 +119,47 @@ public void ConfigureServices(IServiceCollection services)
 
 Again, I can have in-memory subscriptions on one schema and Redis subscriptions on the other.
 
+Next we need to define our `Mutation` type in order to trigger subscriptions whenever something happens on our server.
+
+```csharp
+public class Mutation
+{
+    public string SendMessage(
+        string userId
+        string message,
+        [Service] ITopicEventSender eventSender)
+    {
+        eventSender.SendAsync(userId, message);
+        return message;
+    }
+}
+```
+
+In our example we have a mutation that can send a text message to a user represented by the user API. In order to send a message to our subscription bus we are using the userId argument as a topic and the message as a payload and use the injected `ITopicEventSender` to send the message.
+
+In our subscription type we do not need to handle the receive process or anything. We just specify what the topic is and what the message is and everything will be automatically injected.
+
+```csharp
+public class Subscription
+{
+    [Subscribe]
+    public string OnMessage(
+        [Topic] string userId,
+        [EventMessage] string message) =>
+        message;
+}
+```
+
+The userId in this instance is an argument that is provided from the outside, whereas the message is a parameter where the subscription bus injects the sent message into our resolver.
+
+```graphql
+subscription onMessage {
+  onMessage(userId: "123");
+}
+```
+
+There are a lot more variants with the new subscriptions but I will cover that in a later blog post that only looks at subscriptions and what we can do with them.
+
+## Extensibility
+
+We put a big emphasis