public StsAuthenticationHandler(Configuration.PackageSource packageSource, TokenStore tokenStore, Func <string, string, string> tokenFactory)
        {
            if (packageSource == null)
            {
                throw new ArgumentNullException(nameof(packageSource));
            }

            _baseUri = packageSource.SourceUri;

            if (tokenStore == null)
            {
                throw new ArgumentNullException(nameof(tokenStore));
            }

            _tokenStore = tokenStore;

            if (tokenFactory == null)
            {
                throw new ArgumentNullException(nameof(tokenFactory));
            }

            _tokenFactory = tokenFactory;
        }
 public StsAuthenticationHandler(Configuration.PackageSource packageSource, TokenStore tokenStore)
     : this(packageSource, tokenStore, tokenFactory : (endpoint, realm) => AcquireSTSToken(endpoint, realm))
 {
 }