fixed accept header

Author: thefringeninja

src/SqlStreamStore.HAL/HttpContextExtensions.cs

@@ -13,7 +13,8 @@ internal static class HttpContextExtensions
         private static readonly JsonSerializer s_serializer = JsonSerializer.Create(new JsonSerializerSettings
         {
             ContractResolver = new CamelCasePropertyNamesContractResolver(),
-            TypeNameHandling = TypeNameHandling.None
+            TypeNameHandling = TypeNameHandling.None,
+            NullValueHandling = NullValueHandling.Ignore
         });
 
         public static async Task WriteHalResponse(this HttpContext context, Response response)

src/SqlStreamStore.HAL/SqlStreamStoreHalMiddleware.cs

@@ -29,7 +29,7 @@ private static MidFunc MethodsNotAllowed(params string[] methods) => (context, n
 
         private static MidFunc AcceptOnlyHalJson => (context, next) =>
         {
-            var accept = context.Request.Headers["Accept"]
+            var accept = context.Request.Headers.GetCommaSeparatedValues("Accept")
                 .Select(value => MediaTypeWithQualityHeaderValue.TryParse(value, out var header)
                     ? header.MediaType
                     : null);