PayWithAmazon\Client::checkConfigKeys PHP Method

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