ConverterDocumentPayment::sanitizeFields

public function sanitizeFields($payment=null, array &$fields)
    {
        if(!empty($payment) && !($payment instanceof Payment))
            throw new ArgumentException("Entity must be instanceof Payment");

        foreach($fields as $k=>$v)
        {
            switch($k)
            {
                case 'AMOUNT':
                    if(!empty($payment) && $payment->isPaid())
                    {
                        unset($fields['SUM']);
                    }
                    break;
			case 'PAY_SYSTEM_ID':
				if(!empty($payment))
				{
					unset($fields['PAY_SYSTEM_ID']);
				}
				break;
            }
        }

        if(empty($payment))
        {
            $fields['CURRENCY'] = $this->settings->getCurrency();
        }
        unset($fields['ID']);
    }