outT.cs

outT.cs

interface IRequest<out T>
{
    T Create();
}

class WebRequest<T> : IRequest<T>
{
    public virtual T Create() { return default; }
}

class HttpWebRequest1 : WebRequest<HttpWebRequest1>
{
    public override HttpWebRequest1 Create() { return null; }
}

class HttpWebRequest2 : WebRequest<HttpWebRequest2>
{
    public override HttpWebRequest2 Create() { return null; }
}