public static UserAgent newDeviceUserAgent(IEvidence evidence)
 {
     String ua = evidence.Get("x-device-user-agent");
     if (ua == null || ua.Trim().Length < 2)
     {
         ua = evidence.Get("user-agent");
     }
     return newUserAgent(ua);
 }
 public static UserAgent newBrowserUserAgent(IEvidence evidence)
 {
     return newUserAgent(evidence.Get("user-agent"));
 }