curl --request POST \
  --url https://server.twicecommerce.com/v1/admin/catalog/{id}/add-ons \
  --header 'Content-Type: application/json' \
  --header 'X-API-KEY: <api-key>' \
  --data '
{
  "addonCatalogItemId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "defaultQuantity": 1,
  "quantityMode": "selectable",
  "defaultVariantValueIds": [],
  "defaultSelected": false,
  "required": false,
  "orderIndex": 0
}
'

import requests

url = "https://server.twicecommerce.com/v1/admin/catalog/{id}/add-ons"

payload = {
    "addonCatalogItemId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "defaultQuantity": 1,
    "quantityMode": "selectable",
    "defaultVariantValueIds": [],
    "defaultSelected": False,
    "required": False,
    "orderIndex": 0
}
headers = {
    "X-API-KEY": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'X-API-KEY': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    addonCatalogItemId: '3c90c3cc-0d44-4b50-8888-8dd25736052a',
    defaultQuantity: 1,
    quantityMode: 'selectable',
    defaultVariantValueIds: [],
    defaultSelected: false,
    required: false,
    orderIndex: 0
  })
};

fetch('https://server.twicecommerce.com/v1/admin/catalog/{id}/add-ons', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://server.twicecommerce.com/v1/admin/catalog/{id}/add-ons",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'addonCatalogItemId' => '3c90c3cc-0d44-4b50-8888-8dd25736052a',
    'defaultQuantity' => 1,
    'quantityMode' => 'selectable',
    'defaultVariantValueIds' => [
        
    ],
    'defaultSelected' => false,
    'required' => false,
    'orderIndex' => 0
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "X-API-KEY: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://server.twicecommerce.com/v1/admin/catalog/{id}/add-ons"

	payload := strings.NewReader("{\n  \"addonCatalogItemId\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"defaultQuantity\": 1,\n  \"quantityMode\": \"selectable\",\n  \"defaultVariantValueIds\": [],\n  \"defaultSelected\": false,\n  \"required\": false,\n  \"orderIndex\": 0\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("X-API-KEY", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://server.twicecommerce.com/v1/admin/catalog/{id}/add-ons")
  .header("X-API-KEY", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"addonCatalogItemId\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"defaultQuantity\": 1,\n  \"quantityMode\": \"selectable\",\n  \"defaultVariantValueIds\": [],\n  \"defaultSelected\": false,\n  \"required\": false,\n  \"orderIndex\": 0\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://server.twicecommerce.com/v1/admin/catalog/{id}/add-ons")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["X-API-KEY"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"addonCatalogItemId\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\",\n  \"defaultQuantity\": 1,\n  \"quantityMode\": \"selectable\",\n  \"defaultVariantValueIds\": [],\n  \"defaultSelected\": false,\n  \"required\": false,\n  \"orderIndex\": 0\n}"

response = http.request(request)
puts response.read_body

{
  "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "catalogItemId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "addonCatalogItemId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "defaultQuantity": 1,
  "quantityMode": "selectable",
  "defaultVariantValueIds": [],
  "defaultSelected": false,
  "required": false,
  "orderIndex": 0,
  "purchaseType": "booking",
  "addonCatalogItem": {
    "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "name": "<string>",
    "addonPricingMode": "standalone"
  }
}