fix: register api explorer in sandbox host

F4SDM42WebApi/F4SDM42DependencyRegistrator.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Web.Http;
+using System.Web.Http.Description;
+
+using Matrix42.Hosting.Contracts;
+
+using C4IT.Logging;
+
+using static C4IT.Logging.cLogManager;
+
+namespace C4IT.F4SD
+{
+    public class F4SDM42DependencyRegistrator : IDependencyRegistrator
+    {
+        public void Register(IDependencyContainer container, IDependencyResolver resolver)
+        {
+            if (container == null)
+                throw new ArgumentNullException(nameof(container));
+
+            if (resolver == null)
+                throw new ArgumentNullException(nameof(resolver));
+
+            try
+            {
+                if (resolver.TryGet(typeof(IApiExplorer)) != null)
+                    return;
+            }
+            catch
+            {
+                // Existing mapping is incomplete in the sandbox host. Register a concrete instance below.
+            }
+
+            var httpConfiguration = new HttpConfiguration();
+            container.RegisterInstance(typeof(IApiExplorer), new ApiExplorer(httpConfiguration));
+            LogEntry("Registered System.Web.Http.Description.IApiExplorer for Matrix42 sandbox host.", LogLevels.Debug);
+        }
+    }
+}