curl --request POST \
  --url https://api.withflex.com/v1/checkout/sessions/{id}/refund_allocation \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "checkout_session": {
    "refund_metadata": {
      "order_id": "8842",
      "channel": "shopify"
    },
    "amount_tax": 2500,
    "amount_shipping": 2500,
    "amount_discount": 2500,
    "payment_methods": [
      {
        "payment_method_id": "fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA",
        "amount": 2500
      }
    ],
    "line_items": [
      {
        "amount_to_refund": 2500,
        "product": "fprod_01J9XR8M3K7VZ8N2YB4WJ6T0RA",
        "price": "fprice_01J9XR8M3K7VZ8N2YB4WJ6T0RA"
      }
    ],
    "amount": 0
  }
}
'

import requests

url = "https://api.withflex.com/v1/checkout/sessions/{id}/refund_allocation"

payload = { "checkout_session": {
        "refund_metadata": {
            "order_id": "8842",
            "channel": "shopify"
        },
        "amount_tax": 2500,
        "amount_shipping": 2500,
        "amount_discount": 2500,
        "payment_methods": [
            {
                "payment_method_id": "fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA",
                "amount": 2500
            }
        ],
        "line_items": [
            {
                "amount_to_refund": 2500,
                "product": "fprod_01J9XR8M3K7VZ8N2YB4WJ6T0RA",
                "price": "fprice_01J9XR8M3K7VZ8N2YB4WJ6T0RA"
            }
        ],
        "amount": 0
    } }
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    checkout_session: {
      refund_metadata: {order_id: '8842', channel: 'shopify'},
      amount_tax: 2500,
      amount_shipping: 2500,
      amount_discount: 2500,
      payment_methods: [{payment_method_id: 'fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA', amount: 2500}],
      line_items: [
        {
          amount_to_refund: 2500,
          product: 'fprod_01J9XR8M3K7VZ8N2YB4WJ6T0RA',
          price: 'fprice_01J9XR8M3K7VZ8N2YB4WJ6T0RA'
        }
      ],
      amount: 0
    }
  })
};

fetch('https://api.withflex.com/v1/checkout/sessions/{id}/refund_allocation', 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://api.withflex.com/v1/checkout/sessions/{id}/refund_allocation",
  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([
    'checkout_session' => [
        'refund_metadata' => [
                'order_id' => '8842',
                'channel' => 'shopify'
        ],
        'amount_tax' => 2500,
        'amount_shipping' => 2500,
        'amount_discount' => 2500,
        'payment_methods' => [
                [
                                'payment_method_id' => 'fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA',
                                'amount' => 2500
                ]
        ],
        'line_items' => [
                [
                                'amount_to_refund' => 2500,
                                'product' => 'fprod_01J9XR8M3K7VZ8N2YB4WJ6T0RA',
                                'price' => 'fprice_01J9XR8M3K7VZ8N2YB4WJ6T0RA'
                ]
        ],
        'amount' => 0
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($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://api.withflex.com/v1/checkout/sessions/{id}/refund_allocation"

	payload := strings.NewReader("{\n  \"checkout_session\": {\n    \"refund_metadata\": {\n      \"order_id\": \"8842\",\n      \"channel\": \"shopify\"\n    },\n    \"amount_tax\": 2500,\n    \"amount_shipping\": 2500,\n    \"amount_discount\": 2500,\n    \"payment_methods\": [\n      {\n        \"payment_method_id\": \"fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA\",\n        \"amount\": 2500\n      }\n    ],\n    \"line_items\": [\n      {\n        \"amount_to_refund\": 2500,\n        \"product\": \"fprod_01J9XR8M3K7VZ8N2YB4WJ6T0RA\",\n        \"price\": \"fprice_01J9XR8M3K7VZ8N2YB4WJ6T0RA\"\n      }\n    ],\n    \"amount\": 0\n  }\n}")

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

	req.Header.Add("Authorization", "Bearer <token>")
	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://api.withflex.com/v1/checkout/sessions/{id}/refund_allocation")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"checkout_session\": {\n    \"refund_metadata\": {\n      \"order_id\": \"8842\",\n      \"channel\": \"shopify\"\n    },\n    \"amount_tax\": 2500,\n    \"amount_shipping\": 2500,\n    \"amount_discount\": 2500,\n    \"payment_methods\": [\n      {\n        \"payment_method_id\": \"fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA\",\n        \"amount\": 2500\n      }\n    ],\n    \"line_items\": [\n      {\n        \"amount_to_refund\": 2500,\n        \"product\": \"fprod_01J9XR8M3K7VZ8N2YB4WJ6T0RA\",\n        \"price\": \"fprice_01J9XR8M3K7VZ8N2YB4WJ6T0RA\"\n      }\n    ],\n    \"amount\": 0\n  }\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.withflex.com/v1/checkout/sessions/{id}/refund_allocation")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"checkout_session\": {\n    \"refund_metadata\": {\n      \"order_id\": \"8842\",\n      \"channel\": \"shopify\"\n    },\n    \"amount_tax\": 2500,\n    \"amount_shipping\": 2500,\n    \"amount_discount\": 2500,\n    \"payment_methods\": [\n      {\n        \"payment_method_id\": \"fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA\",\n        \"amount\": 2500\n      }\n    ],\n    \"line_items\": [\n      {\n        \"amount_to_refund\": 2500,\n        \"product\": \"fprod_01J9XR8M3K7VZ8N2YB4WJ6T0RA\",\n        \"price\": \"fprice_01J9XR8M3K7VZ8N2YB4WJ6T0RA\"\n      }\n    ],\n    \"amount\": 0\n  }\n}"

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

{
  "allocations": [
    {
      "payment_method_id": "fpm_01J9XR8M3K7VZ8N2YB4WJ6T0RA",
      "last4": "4242",
      "amount": 2500
    }
  ]
}

{
  "code": "string",
  "detail": "string"
}

{
  "code": "string",
  "detail": "string"
}

{
  "code": "string",
  "detail": "string"
}

{
  "code": "string",
  "detail": "string"
}

{
  "detail": [
    {
      "loc": [
        "string"
      ],
      "msg": "string",
      "type": "string"
    }
  ]
}

{
  "code": "string",
  "detail": "string"
}