[Hierarchy(new string[] { "ProxyAuthScheme=Basic", "ProxyAuthScheme=Digest", "ProxyAuthScheme=Kerberos" })]
public string ProxyServer { get; set; }

<Hierarchy(New String() { "ProxyAuthScheme=Basic", "ProxyAuthScheme=Digest", "ProxyAuthScheme=Kerberos" })>
Public Property ProxyServer As String