Startup.cs

using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.IdentityModel.Tokens;
using Microsoft.OpenApi.Models;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.Json.Serialization;
using System.Threading.Tasks;
using WebAPIAutores.Filtros;
using WebAPIAutores.Middleware;

namespace WebAPIAutores
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {

            //services.AddControllers();
            // Con la opción Json ReferenceHandler.Preserve evito el error por referencias
            // ciruclares de Libros -> Autor -> Libro -> Autor ...
            // En NET 6 existe ReferenceHandler.IgnoreCycles que reemplaza a Preserve y da mejor resultado.
            // Otra cosa a observar es que mediante "options" se agrega un filtro global de Excpeción.
            services.AddControllers(options => options.Filters.Add(typeof(FiltroDeExcepcion)))
                .AddJsonOptions(x => x.JsonSerializerOptions.ReferenceHandler = ReferenceHandler.Preserve)
                .AddNewtonsoftJson();

            services.AddDbContext<ApplicationDbContext>(options => 
                options.UseSqlServer(Configuration.GetConnectionString("defaultConnection")));

            /* Habilita la autenticación para controladoes o simplemente para algunas acciones.
             * Ejemplo: [Authorize] */
            services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
                .AddJwtBearer(opciones => opciones.TokenValidationParameters = new TokenValidationParameters { 
                    ValidateIssuer = false,
                    ValidateAudience = false,
                    ValidateLifetime = true,
                    ValidateIssuerSigningKey = true,
                    IssuerSigningKey = new SymmetricSecurityKey(
                        Encoding.UTF8.GetBytes(Configuration["llavejwt"])),
                    ClockSkew = TimeSpan.Zero
                });

            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "WebAPIAutores", Version = "v1" });

                c.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme
                {
                    Name = "Authorization",
                    Type = SecuritySchemeType.ApiKey,
                    Scheme = "Bearer",
                    BearerFormat = "JWT",
                    In = ParameterLocation.Header
                });

                c.AddSecurityRequirement(new OpenApiSecurityRequirement
                {
                    {
                        new OpenApiSecurityScheme
                        {
                            Reference = new OpenApiReference
                            {
                                Type = ReferenceType.SecurityScheme,
                                Id = "Bearer"
                            }
                        },
                        new string[] {}
                    }
                });
            });

            services.AddAutoMapper(typeof(Startup));

            services.AddIdentity<IdentityUser, IdentityRole>()
                .AddEntityFrameworkStores<ApplicationDbContext>()
                .AddDefaultTokenProviders();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ILogger<Startup> logger)
        {
            //app.UseMiddleware<LogearRespuestaHTTPMiddleware>();
            app.UseLogearRespuestaHTTP();

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseSwagger();
                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "WebAPIAutores v1"));
            }

            app.UseHttpsRedirection();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}