src/Common/Message/AbstractRequest.php
public function setCurrency($value)
    {
        if ($value !== null) {
            $value = strtoupper($value);
        }
        return $this->setParameter('currency', $value);
    }
public function setCurrency($value)
    {
        if ($value !== null) {
            $value = strtoupper($value);
        }
        return $this->setParameter('currency', $value);
    }
Sets the payment currency code.

@param string $value
@return $this