public void Dispose()
 {
     if (http != null)
     {
         http.Dispose();
         http = null;
     }
 }
        public ElevationService(GoogleSigned signingSvc = null, Uri baseUri = null)
        {
            this.baseUri = baseUri ?? HttpsUri;

            this.http = new MapsHttp(signingSvc ?? GoogleSigned.SigningInstance);
        }