Update ServiceBinderBase.AddMethod annotations to allow null handler (#2270)

Author: JamesNK

src/Grpc.AspNetCore.Server/Model/Internal/ProviderServiceBinder.cs

@@ -1,4 +1,4 @@
-#region Copyright notice and license
+#region Copyright notice and license
 
 // Copyright 2019 The gRPC Authors
 //
@@ -39,7 +39,7 @@ internal ProviderServiceBinder(ServiceMethodProviderContext<TService> context, T
         _declaringType = declaringType;
     }
 
-    public override void AddMethod<TRequest, TResponse>(Method<TRequest, TResponse> method, ClientStreamingServerMethod<TRequest, TResponse> handler)
+    public override void AddMethod<TRequest, TResponse>(Method<TRequest, TResponse> method, ClientStreamingServerMethod<TRequest, TResponse>? handler)
     {
         var (invoker, metadata) = CreateModelCore<ClientStreamingServerMethod<TService, TRequest, TResponse>>(
             method.Name,
@@ -48,7 +48,7 @@ public override void AddMethod<TRequest, TResponse>(Method<TRequest, TResponse>
         _context.AddClientStreamingMethod<TRequest, TResponse>(method, metadata, invoker);
     }
 
-    public override void AddMethod<TRequest, TResponse>(Method<TRequest, TResponse> method, DuplexStreamingServerMethod<TRequest, TResponse> handler)
+    public override void AddMethod<TRequest, TResponse>(Method<TRequest, TResponse> method, DuplexStreamingServerMethod<TRequest, TResponse>? handler)
     {
         var (invoker, metadata) = CreateModelCore<DuplexStreamingServerMethod<TService, TRequest, TResponse>>(
             method.Name,
@@ -57,7 +57,7 @@ public override void AddMethod<TRequest, TResponse>(Method<TRequest, TResponse>
         _context.AddDuplexStreamingMethod<TRequest, TResponse>(method, metadata, invoker);
     }
 
-    public override void AddMethod<TRequest, TResponse>(Method<TRequest, TResponse> method, ServerStreamingServerMethod<TRequest, TResponse> handler)
+    public override void AddMethod<TRequest, TResponse>(Method<TRequest, TResponse> method, ServerStreamingServerMethod<TRequest, TResponse>? handler)
     {
         var (invoker, metadata) = CreateModelCore<ServerStreamingServerMethod<TService, TRequest, TResponse>>(
             method.Name,
@@ -66,7 +66,7 @@ public override void AddMethod<TRequest, TResponse>(Method<TRequest, TResponse>
         _context.AddServerStreamingMethod<TRequest, TResponse>(method, metadata, invoker);
     }
 
-    public override void AddMethod<TRequest, TResponse>(Method<TRequest, TResponse> method, UnaryServerMethod<TRequest, TResponse> handler)
+    public override void AddMethod<TRequest, TResponse>(Method<TRequest, TResponse> method, UnaryServerMethod<TRequest, TResponse>? handler)
     {
         var (invoker, metadata) = CreateModelCore<UnaryServerMethod<TService, TRequest, TResponse>>(
             method.Name,

src/Grpc.Core.Api/ServiceBinderBase.cs

@@ -40,7 +40,7 @@ public class ServiceBinderBase
     /// <param name="handler">The method handler.</param>
     public virtual void AddMethod<TRequest, TResponse>(
         Method<TRequest, TResponse> method,
-        UnaryServerMethod<TRequest, TResponse> handler)
+        UnaryServerMethod<TRequest, TResponse>? handler)
             where TRequest : class
             where TResponse : class
     {
@@ -56,7 +56,7 @@ public virtual void AddMethod<TRequest, TResponse>(
     /// <param name="handler">The method handler.</param>
     public virtual void AddMethod<TRequest, TResponse>(
         Method<TRequest, TResponse> method,
-        ClientStreamingServerMethod<TRequest, TResponse> handler)
+        ClientStreamingServerMethod<TRequest, TResponse>? handler)
             where TRequest : class
             where TResponse : class
     {
@@ -72,7 +72,7 @@ public virtual void AddMethod<TRequest, TResponse>(
     /// <param name="handler">The method handler.</param>
     public virtual void AddMethod<TRequest, TResponse>(
         Method<TRequest, TResponse> method,
-        ServerStreamingServerMethod<TRequest, TResponse> handler)
+        ServerStreamingServerMethod<TRequest, TResponse>? handler)
             where TRequest : class
             where TResponse : class
     {
@@ -88,7 +88,7 @@ public virtual void AddMethod<TRequest, TResponse>(
     /// <param name="handler">The method handler.</param>
     public virtual void AddMethod<TRequest, TResponse>(
         Method<TRequest, TResponse> method,
-        DuplexStreamingServerMethod<TRequest, TResponse> handler)
+        DuplexStreamingServerMethod<TRequest, TResponse>? handler)
             where TRequest : class
             where TResponse : class
     {