我建了一个简单的 .NET 6 WebAPI项目，其中Program.cs是这样的：

using AspNetCoreRateLimit;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.

// IpRateLimit

//需要从加载配置文件appsettings.json
builder.Services.AddOptions();

//需要存储速率限制计算器和ip规则
builder.Services.AddMemoryCache();

//从appsettings.json中加载常规配置
builder.Services.Configure<ClientRateLimitOptions>(Configuration.GetSection("IPRateLimiting"));

//从appsettings.json中加载客户端规则
builder.Services.Configure<ClientRateLimitPolicies>(Configuration.GetSection("ClientRateLimitPolicies"));

//注入计数器和规则存储
builder.Services.AddSingleton<IClientPolicyStore, MemoryCacheClientPolicyStore>();
builder.Services.AddSingleton<IRateLimitCounterStore, MemoryCacheRateLimitCounterStore>();
//end of IpLimit

builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
app.UseSwagger();
app.UseSwaggerUI();
}
app.UseAuthorization();

app.MapControllers();

app.Run();

但是其中的Configuration.GetSection()编译通不过，我也不知道应该引入哪一个命名空间？