Startup.cs

using JWT.Algorithms;
using JWT.Builder;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.OpenApi.Models;
using StackUnderflow.Configuration;
using StackUnderflow.Entities;
using System;
using System.Collections.Generic;

namespace StackUnderflow
{
    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.Configure<JwtConfig>(Configuration.GetSection("JwtConfig"));

            services.AddDbContext<StackUnderflowContext>();

          
            services.AddCors(options =>
            {
                options.AddDefaultPolicy(
                    builder =>
                    {
                        builder.AllowAnyOrigin()
                            .AllowAnyHeader()
                            .AllowAnyMethod();
                    });
            });

            services.AddControllers();
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo {Title = "StackUnderflow", Version = "v1"});
            });
            
            services.AddSingleton(new List<string>());
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseSwagger();
                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "StackUnderflow v1"));
            }

            app.UseRouting();
            app.UseCors();
            app.UseAuthentication();
            app.UseAuthorization();

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