Adding working endpoint demo - run it from Swagger

src/CleanArchitecture.Web/Endpoints/BaseEndpoint.cs

+using Microsoft.AspNetCore.Mvc;
+
+namespace CleanArchitecture.Web.Endpoints
+{
+    public abstract class BaseEndpoint<TRequest,TResponse> : ControllerBase
+    {
+        public abstract ActionResult<TResponse> Handle(TRequest request);
+    }
+}

src/CleanArchitecture.Web/Endpoints/ToDoItems/CreateHandler.cs

+using CleanArchitecture.Core.Entities;
+using CleanArchitecture.SharedKernel.Interfaces;
+using Microsoft.AspNetCore.Mvc;
+using System.ComponentModel.DataAnnotations;
+
+namespace CleanArchitecture.Web.Endpoints.ToDoItems
+{
+    public class CreateHandler : BaseEndpoint<CreateCommand, CreatedResult>
+    {
+        private readonly IRepository _repository;
+
+        public CreateHandler(IRepository repository)
+        {
+            _repository = repository;
+        }
+
+        [HttpPost("/endpoints/items")]
+        public override ActionResult<CreatedResult> Handle([FromBody]CreateCommand request)
+        {
+            var todoItem = new ToDoItem()
+            {
+                Title = request.Title,
+                Description = request.Description
+            };
+            _repository.Add(todoItem);
+
+            var result = new CreatedResult
+            {
+                Id = todoItem.Id,
+                Title = todoItem.Title,
+                Description = todoItem.Description
+            };
+            return Ok(result);
+        }
+    }
+
+    // Imagine these are separate classes attached to the Handler/Endpoint with + expansion in VS
+    public class CreateCommand
+    {
+        [Required]
+        public string Title { get; set; }
+        [Required]
+        public string Description { get; set; }
+    }
+
+    public class CreatedResult : CreateCommand
+    {
+        public int Id { get; set; }
+    }
+
+}