如何使用类属性中的TypeDescriptor.GetProperties获取具有自定义属性的属性？

Question

与this question一样，我想使用TypeDescriptor来获取一些属性 - 但与那个问题不同，我想只获取已经添加了自定义属性的属性。

这是一个类属性，所以我想获得具有自定义属性的类中的属性。

到目前为止我有什么

[AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = true)]
public class AtLeastOneValueRequiredClassAttribute : ValidationAttribute
{
    public override bool IsValid(object selection)
    {
        var att = new Attribute[] { new AtLeastOneValueRequiredAttribute() };

        PropertyDescriptorCollection properties = 
            TypeDescriptor.GetProperties(selection, att);

        foreach (var property in properties)
        {
            if (property != null)
                return true;
        }
        return false;
    }

...始终返回所有属性，而不仅仅是具有我的自定义属性属性的属性（AtLeastOneValueRequiredAttribute）。

以下是我将其应用于此类的课程：

[AtLeastOneValueRequiredClassAttribute(ErrorMessage = "You must enter at least one number")]
public class MemberDetails
{
    [AtLeastOneValueRequired]
    [Display(Name = "Home Phone Number")]
    [RegularExpression("([0-9]+)", ErrorMessage = "Please provide a valid Home Phone number")]
    public string HomePhoneNumber { get; set; }

    [AtLeastOneValueRequired]
    [Display(Name = "Work Phone Number")]
    [RegularExpression("([0-9]+)", ErrorMessage = "Please provide a valid Work Phone number")]
    public string WorkPhoneNumber { get; set; }

    [AtLeastOneValueRequired]
    [Display(Name = "Fax Number")]
    [RegularExpression("([0-9]+)", ErrorMessage = "Please provide a valid Fax number")]
    public string FaxNumber { get; set; }

    [AtLeastOneValueRequired]
    [Display(Name = "Mobile Number")]
    [RegularExpression("([0-9]+)", ErrorMessage = "Please provide a valid Mobile Phone number")]
    public string MobileNumber { get; set; }
}