<?php

$body = json_encode(
    [
        'stamp' =>  'unique-identifier-for-merchant',
        'reference' => '3759170',
        'amount' => 1525,
        'currency' => 'EUR',
        'language' => 'FI',
        'items' => [
            [
                'unitPrice' => 1525,
                'units' => 1,
                'vatPercentage' => 24,
                'productCode' => '#1234',
                'deliveryDate' => '2018-09-01'
            ]
        ],
        'customer' => [
            'email' => 'test.customer@example.com'
        ],
        'redirectUrls' => [
            'success' => 'https://ecom.example.com/cart/success',
            'cancel' => 'https://ecom.example.com/cart/cancel'
        ]
    ],
    JSON_UNESCAPED_SLASHES
);

echo($body);

?>