protected function convertJwtToOAuth2($tokenData)
    {
        $keyMapping = array(
            'aud' => 'client_id',
            'exp' => 'expires',
            'sub' => 'user_id'
        );

        foreach ($keyMapping as $jwtKey => $oauth2Key) {
            if (isset($tokenData[$jwtKey])) {
                $tokenData[$oauth2Key] = $tokenData[$jwtKey];
                unset($tokenData[$jwtKey]);
            }
        }

        return $tokenData;
    }