Fixing ambiguous HTTP methods as warned by Swagger

Lombiq.TrainingDemo/Controllers/CrossTenantServicesController.cs

@@ -35,7 +35,7 @@ public class CrossTenantServicesController : Controller
     // A simple route for convenience. You can access this from under /CrossTenantServices?contentItemId=ID. Here ID
     // needs to be a content item ID that you can get e.g. from the URL when you open an item to edit from the admin (it
     // looks something like "4da2sme18cc2k2r5d4w23d4cwj" which is NOT made by a cat walking across the keyboard!).
-    [Route("CrossTenantServices")]
+    [HttpGet, Route("CrossTenantServices")]
     public async Task<string> Index(string contentItemId)
     {
         // If ModelState is not in a valid state we should abort the action and return null.

Lombiq.TrainingDemo/Controllers/YourFirstOrchardCoreController.cs

@@ -59,7 +59,7 @@ public ActionResult Index()
     }
 
     // Let's see some custom routing here. This attribute will override the default route and use this one.
-    [Route("TrainingDemo/NotifyMe")]
+    [HttpGet, Route("TrainingDemo/NotifyMe")]
     public async Task<IActionResult> NotifyMe()
     {
         // ILogger is an ASP.NET Core service that will write something into the specific log files. In Orchard Core