Add AddMqttDefaultJsonOptions extension

Author: seikosantana

Source/Extensions/ServiceCollectionExtensions.cs

@@ -6,6 +6,7 @@
 using System;
 using System.Reflection;
 using System.Runtime.CompilerServices;
+using System.Text.Json;
 
 // This is needed to make internal classes visible to UnitTesting projects
 [assembly: InternalsVisibleTo("MQTTnet.AspNetCore.Routing.Tests, PublicKey=00240000048000009" +
@@ -38,6 +39,13 @@ public static IServiceCollection AddMqttControllers(this IServiceCollection serv
             return services;
         }
 
+        public static IServiceCollection AddMqttDefaultJsonOptions(this IServiceCollection services,
+            JsonSerializerOptions options)
+        {
+            services.AddSingleton(new MqttDefaultJsonOptions(options));
+            return services;
+        }
+
         public static void WithAttributeRouting(this MqttServer server, IServiceProvider svcProvider, bool allowUnmatchedRoutes = false)
         {
             var router = svcProvider.GetRequiredService<MqttRouter>();