Add CanBeNull attribute.

framework/src/Volo.Abp.Json/Volo/Abp/Json/IJsonSerializerProvider.cs

@@ -1,10 +1,11 @@
 using System;
+using JetBrains.Annotations;
 
 namespace Volo.Abp.Json
 {
     public interface IJsonSerializerProvider
     {
-        bool CanHandle(Type type);
+        bool CanHandle([CanBeNull]Type type);
 
         string Serialize(object obj, bool camelCase = true, bool indented = false);
 

framework/src/Volo.Abp.Json/Volo/Abp/Json/SystemTextJson/AbpSystemTextJsonUnsupportedTypeMatcher.cs

@@ -1,4 +1,5 @@
 using System;
+using JetBrains.Annotations;
 using Microsoft.Extensions.Options;
 using Volo.Abp.DependencyInjection;
 
@@ -13,7 +14,7 @@ namespace Volo.Abp.Json.SystemTextJson
             Options = options.Value;
         }
 
-        public virtual bool Match(Type type)
+        public virtual bool Match([CanBeNull]Type type)
         {
             return Options.UnsupportedTypes.Contains(type);
         }