public static function getJson()
{
return '{"custom":"TestSample","invoice_number":"TestSample","refund_to_payer":' . CurrencyTest::getJson() . ',"refund_to_external_funding":' . ExternalFundingTest::getJson() . ',"refund_from_transaction_fee":' . CurrencyTest::getJson() . ',"refund_from_received_amount":' . CurrencyTest::getJson() . ',"total_refunded_amount":' . CurrencyTest::getJson() . '}';
}