refreshAccessToken method
Refresh Access Token
Implementation
Future<OAuthToken> refreshAccessToken() async {
OAuthToken? token = await this.storage.fetch();
if (token?.refreshToken == null) {
throw OAuthException('missing_refresh_token', 'Missing refresh token!');
}
return this.requestTokenAndSave(
RefreshTokenGrant(refreshToken: token!.refreshToken!));
}