Using [NotNull]

src/Microsoft.AspNet.WebSockets.Protocol/HandshakeHelpers.cs

@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.Security.Cryptography;
 using System.Text;
+using Microsoft.Framework.Internal;
 
 namespace Microsoft.AspNet.WebSockets.Protocol
 {
@@ -123,13 +124,8 @@ namespace Microsoft.AspNet.WebSockets.Protocol
         /// </summary>
         /// <param name="requestKey"></param>
         /// <returns></returns>
-        public static string CreateResponseKey(string requestKey)
+        public static string CreateResponseKey([NotNull] string requestKey)
         {
-            if (string.IsNullOrWhiteSpace(requestKey))
-            {
-                throw new ArgumentNullException("requestKey");
-            }
-
             using (var algorithm = SHA1.Create())
             {
                 string merged = requestKey + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";

src/Microsoft.AspNet.WebSockets.Protocol/project.json

@@ -1,6 +1,9 @@
 {
     "version": "1.0.0-*",
     "description": "Managed web socket protocol parser.",
+    "dependencies": {
+        "Microsoft.Framework.NotNullAttribute.Internal": { "type": "build", "version": "1.0.0-*" }
+    },
     "frameworks": {
         "net45": { },
         "dnxcore50": {

test/Microsoft.AspNet.WebSockets.Protocol.Test/BufferStream.cs

@@ -7,6 +7,7 @@ using System.Diagnostics.Contracts;
 using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.Framework.Internal;
 
 namespace Microsoft.AspNet.WebSockets.Protocol.Test
 {
@@ -255,12 +256,8 @@ namespace Microsoft.AspNet.WebSockets.Protocol.Test
             return Task.FromResult<object>(null);
         }
 
-        private static void VerifyBuffer(byte[] buffer, int offset, int count, bool allowEmpty)
+        private static void VerifyBuffer([NotNull] byte[] buffer, int offset, int count, bool allowEmpty)
         {
-            if (buffer == null)
-            {
-                throw new ArgumentNullException("buffer");
-            }
             if (offset < 0 || offset > buffer.Length)
             {
                 throw new ArgumentOutOfRangeException(nameof(offset), offset, string.Empty);

test/Microsoft.AspNet.WebSockets.Protocol.Test/project.json

@@ -1,6 +1,7 @@
 {
     "dependencies": {
         "Microsoft.AspNet.WebSockets.Protocol": "1.0.0-*",
+        "Microsoft.Framework.NotNullAttribute.Internal": { "type": "build", "version": "1.0.0-*" },
         "xunit.runner.aspnet": "2.0.0-aspnet-*"
     },
     "frameworks": {