https://docs.mollie.com/reference/v2/payments-api/get-payment
function(string $api_key, string $payment_id, array $params = [])
{
$mollie = new MollieApiClient();
$mollie->setApiKey($api_key);
$payment = $mollie->payments->get($payment_id, $params);
return X::toArray($payment);
}