PAYPAL php SDK v1.0.1，无法设置收款方邮箱

composer require paypal/rest-api-sdk-php

require 'vendor/autoload.php';

use PayPal\Api\Payer;
use PayPal\Api\PaymentExecution;
use PayPal\Api\Payment;
use PayPal\Api\Transaction;
use PayPal\Api\FundingInstrument;
use PayPal\Api\Amount;
use PayPal\Api\Details;
use PayPal\Api\PaymentExecutionParameters;

$apiContext = new \PayPal\Rest\ApiContext(
    new \PayPal\Auth\OAuthTokenCredential(
        'CLIENT_ID',
        'CLIENT_SECRET'
    )
);

$payer = new Payer();
$payer->setPaymentMethod('paypal');

$amount = new Amount();
$amount->setTotal('10.00');
$amount->setCurrency('USD');

$details = new Details();
$details->setSubtotal('10.00');

$transaction = new Transaction();
$transaction->setAmount($amount);
$transaction->setDescription('Transaction description');
$transaction->setInvoiceNumber(uniqid());

$fundingInstrument = new FundingInstrument();
$fundingInstrument->setPayerPaymentMethod('paypal');

$payer->setPaymentMethod('paypal');
$payer->setPayerInfo([
    'email' => 'payer@example.com'
]);

$payment = new Payment();
$payment->setIntent('sale');
$payment->setPayer($payer);
$payment->setTransactions([$transaction]);
$payment->setCreateTime(date('Y-m-d\TH:i:s\Z'));
$payment->setUpdateTime(date('Y-m-d\TH:i:s\Z'));

$payment->create($apiContext);

// 手动设置收款方邮箱
$execution = new PaymentExecution();
$execution->setPayerId($payment->getPayer()->getPayerInfo()->getEmail());
$execution->setTransactions([$transaction]);

$payment->execute($apiContext, $execution);