refactor

src/Cap.Consistency/Microsoft.AspNetCore.Builder/BuilderExtensions.cs

+using System;
+using Cap.Consistency;
+using Microsoft.Extensions.DependencyInjection;
+
+// ReSharper disable once CheckNamespace
+namespace Microsoft.AspNetCore.Builder
+{
+    /// <summary>
+    /// Consistence extensions for <see cref="IApplicationBuilder"/>
+    /// </summary>
+    public static class BuilderExtensions
+    {
+        ///<summary>
+        /// Enables Consistence for the current application
+        /// </summary>
+        /// <param name="app">The <see cref="IApplicationBuilder"/> instance this method extends.</param>
+        /// <returns>The <see cref="IApplicationBuilder"/> instance this method extends.</returns>
+        public static IApplicationBuilder UseConsistency(this IApplicationBuilder app) {
+            if (app == null) {
+                throw new ArgumentNullException(nameof(app));
+            }
+            
+            var marker = app.ApplicationServices.GetService<ConsistencyMarkerService>();
+         
+            if (marker == null) {
+                throw new InvalidOperationException("Add Consistency must be called on the service collection.");
+            }
+
+            var router = app.ApplicationServices.GetService<ITopicRouteHandler>();
+
+            var context = new TopicRouteContext();
+
+            router.RouteAsync(context);
+
+            return app;
+        }
+
+    }
+}
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