curl --request PATCH \
  --url https://api.example.com/api/v1/invoices/{invoice_id}/custom-properties \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "custom_properties": "<unknown>"
}
'

import requests

url = "https://api.example.com/api/v1/invoices/{invoice_id}/custom-properties"

payload = { "custom_properties": "<unknown>" }
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'PATCH',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({custom_properties: '<unknown>'})
};

fetch('https://api.example.com/api/v1/invoices/{invoice_id}/custom-properties', 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.example.com/api/v1/invoices/{invoice_id}/custom-properties",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "PATCH",
  CURLOPT_POSTFIELDS => json_encode([
    'custom_properties' => '<unknown>'
  ]),
  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.example.com/api/v1/invoices/{invoice_id}/custom-properties"

	payload := strings.NewReader("{\n  \"custom_properties\": \"<unknown>\"\n}")

	req, _ := http.NewRequest("PATCH", 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.patch("https://api.example.com/api/v1/invoices/{invoice_id}/custom-properties")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"custom_properties\": \"<unknown>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.example.com/api/v1/invoices/{invoice_id}/custom-properties")

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

request = Net::HTTP::Patch.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"custom_properties\": \"<unknown>\"\n}"

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

{
  "amount_due": 123,
  "applied_credits": 123,
  "coupons": [
    {
      "coupon_id": "<string>",
      "name": "<string>",
      "total": 123
    }
  ],
  "created_at": "2023-11-07T05:31:56Z",
  "currency": "EUR",
  "custom_properties": "<unknown>",
  "customer_details": {
    "id": "cus_7n42DGM5Tflk9n8mt7Fhc7",
    "name": "<string>",
    "snapshot_at": "2023-11-07T05:31:56Z",
    "alias": "<string>",
    "billing_address": {
      "city": "<string>",
      "country": "US",
      "line1": "<string>",
      "line2": "<string>",
      "state": "<string>",
      "zip_code": "<string>"
    },
    "email": "<string>",
    "vat_number": "<string>"
  },
  "customer_id": "cus_7n42DGM5Tflk9n8mt7Fhc7",
  "id": "inv_7n42DGM5Tflk9n8mt7Fhc7",
  "invoice_date": "2023-12-25",
  "invoice_number": "<string>",
  "invoice_type": "RECURRING",
  "line_items": [
    {
      "amount_total": 123,
      "end_date": "2023-12-25",
      "name": "<string>",
      "start_date": "2023-12-25",
      "sub_line_items": [
        {
          "id": "<string>",
          "name": "<string>",
          "quantity": "<string>",
          "total": 123,
          "unit_price": "<string>"
        }
      ],
      "tax_rate": "<string>",
      "description": "<string>",
      "quantity": "<string>",
      "unit_price": "<string>"
    }
  ],
  "net_terms": 123,
  "payment_status": "UNPAID",
  "status": "DRAFT",
  "subtotal": 123,
  "subtotal_recurring": 123,
  "tax_amount": 123,
  "tax_breakdown": [
    {
      "name": "<string>",
      "tax_amount": 123,
      "tax_rate": "<string>",
      "taxable_amount": 123,
      "exemption_reason": "<string>",
      "exemption_type": "REVERSE_CHARGE",
      "tax_reference": "<string>"
    }
  ],
  "total": 123,
  "transactions": [
    {
      "amount": 1,
      "currency": "<string>",
      "id": "pay_7n42DGM5Tflk9n8mt7Fhc7",
      "payment_type": "PAYMENT",
      "status": "READY",
      "error": "<string>",
      "payment_method_id": "pm_7n42DGM5Tflk9n8mt7Fhc7",
      "payment_method_info": {
        "payment_method_type": "CARD",
        "account_number_hint": "<string>",
        "card_brand": "<string>",
        "card_last4": "<string>"
      },
      "processed_at": "2023-11-07T05:31:56Z",
      "provider_transaction_id": "<string>"
    }
  ],
  "billing_period_start": "2023-12-25",
  "child_invoice_id": "inv_7n42DGM5Tflk9n8mt7Fhc7",
  "due_date": "2023-12-25",
  "finalized_at": "2023-11-07T05:31:56Z",
  "marked_as_uncollectible_at": "2023-11-07T05:31:56Z",
  "memo": "<string>",
  "paid_at": "2023-11-07T05:31:56Z",
  "parent_invoice_id": "inv_7n42DGM5Tflk9n8mt7Fhc7",
  "purchase_order": "<string>",
  "reference": "<string>",
  "subscription_id": "sub_7n42DGM5Tflk9n8mt7Fhc7",
  "updated_at": "2023-11-07T05:31:56Z",
  "voided_at": "2023-11-07T05:31:56Z"
}

{
  "code": "BAD_REQUEST",
  "message": "<string>"
}

{
  "code": "BAD_REQUEST",
  "message": "<string>"
}

{
  "code": "BAD_REQUEST",
  "message": "<string>"
}

{
  "code": "BAD_REQUEST",
  "message": "<string>"
}

{
  "code": "BAD_REQUEST",
  "message": "<string>"
}