PayWithAmazon\IpnHandler::checkConfigKeys PHP Method

    private function checkConfigKeys($ipnConfig)
    {
        $ipnConfig = array_change_key_case($ipnConfig, CASE_LOWER);
        $ipnConfig = $this->trimArray($ipnConfig);
        foreach ($ipnConfig as $key => $value) {
            if (array_key_exists($key, $this->ipnConfig)) {
                $this->ipnConfig[$key] = $value;
            } else {
                throw new \Exception('Key ' . $key . ' is either not part of the configuration or has incorrect Key name.
                check the ipnConfig array key names to match your key names of your config array ', 1);
            }
        }
    }