Autofac注册了两次AuthorizationFilter调用

嗨，我有一个授权过滤器，它是使用Autofac对WebApi的支持创建的。总结如下：

public class ApplicationTokenValidatorAttribute : IAutofacAuthorizationFilter
{
    //...
    /// <summary>
    /// Default constructor for ApplicationTokenValidatorAttribute
    /// </summary>
    /// <param name="tenancyClient">Tenancy service used to resolve application key checks and populate tenancy object on valid controllers</param>
    /// <param name="commonServices">Provides access to commonly used services, including logging and performance tracing</param>
    public ApplicationTokenValidatorAttribute(ITenancyClient tenancyClient, ICommonServices commonServices)
    {
        _tenancyClient = tenancyClient;
        _commonServices = commonServices;
    }
    /// <summary>
    /// Pass/fails authentication, based on whether you provide a valid application key in the http headers of the request
    /// </summary>
    /// <param name="actionContext">Action filter context</param>
    public void OnAuthorization(HttpActionContext actionContext)
    {
        //...
    }

我不认为过滤器中的实际代码很重要，但如果有人不这么认为，那么我可以检查它并粘贴更多。

我使用这个autofac代码注册它

builder.RegisterWebApiFilterProvider(GlobalConfiguration.Configuration);
builder.Register(c => 
    new ApplicationTokenValidatorAttribute(
            c.Resolve<ITenancyClient>(),
            c.Resolve<ICommonServices>()))
        .AsWebApiAuthorizationFilterFor<TenantAwareApiController>()
        .InstancePerApiRequest();

我认为是在https://code.google.com/p/autofac/wiki/WebApiIntegration.

然而，如果我这样做，它会为每个请求调用两次。

如果我注释掉行

builder.RegisterWebApiFilterProvider(GlobalConfiguration.Configuration);

那么过滤器只被调用一次。有人能解释一下吗？我需要这条线吗？我不愿意排除文件中特别列出的声明，但它似乎是问题的根源。

欢呼，

p

builder.RegisterWebApiFilterProvider(GlobalConfiguration.Configuration);