json不忽略null值

performance/Performance.Infrastructure/Helper/JsonHelper.cs

@@ -21,7 +21,7 @@ static JsonHelper()
             _jsonSettings = new JsonSerializerSettings
             {
                 MissingMemberHandling = MissingMemberHandling.Ignore,
-                NullValueHandling = NullValueHandling.Ignore,
+                NullValueHandling = NullValueHandling.Include,
                 ReferenceLoopHandling = ReferenceLoopHandling.Ignore
             };
             _jsonSettings.Converters.Add(datetimeConverter);