public function setOnlineBankDebit($bankNumber, $expirationDate, $returnUri)
    {
        if ($expirationDate instanceof \DateTime) {
            $expirationDate = $expirationDate->format('Y-m-d');
        }
        $this->data->fundingInstrument->method = self::METHOD_ONLINE_BANK_DEBIT;
        $this->data->fundingInstrument->onlineBankDebit = new stdClass();
        $this->data->fundingInstrument->onlineBankDebit->bankNumber = $bankNumber;
        $this->data->fundingInstrument->onlineBankDebit->expirationDate = $expirationDate;
        $this->data->fundingInstrument->onlineBankDebit->returnUri = $returnUri;

        return $this;
    }