PayPal\Api\PaymentDetail::setAmount PHP Method

The amount to record as payment against invoice. If you omit this parameter, the total invoice amount is recorded as payment.

public setAmount ( PayPal\Api\Currency $amount )
$amount	PayPal\Api\Currency

    public function setAmount($amount)
    {
        $this->amount = $amount;
        return $this;
    }

PaymentDetail