Refresh the access token for .Net web applications
          The refresh access token is valid for two hours by default.
         
         If the access token is expired, a new access token can be obtained by using refresh token. These are the parameters used to renew the access token using IFS CE token endpoint.
- grant_type=refresh_token
 - refresh_token
 - client id: Use as the username for HTTP basic authentication
 - client secret: Use as the password for HTTP basic authentication
 
The OAuth client library automatically handles refreshing expired tokens.