curl --request POST \
  --url http://127.0.0.1:8080/v1/c/contract/{contract_id}/upgrade \
  --header 'Content-Type: application/json' \
  --header 'wb-key: <api-key>' \
  --data '
{
  "upgrade_configuration": {
    "activation": {
      "type": "next_cycle"
    },
    "plan_id": "Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670",
    "unit_configuration": {},
    "unit_count_configuration": {},
    "upgrade_strategy": "new_plan",
    "discount_id": "Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670",
    "pricing_id": "Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670"
  },
  "downgrade_allowed": true
}
'

import requests

url = "http://127.0.0.1:8080/v1/c/contract/{contract_id}/upgrade"

payload = {
    "upgrade_configuration": {
        "activation": { "type": "next_cycle" },
        "plan_id": "Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670",
        "unit_configuration": {},
        "unit_count_configuration": {},
        "upgrade_strategy": "new_plan",
        "discount_id": "Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670",
        "pricing_id": "Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670"
    },
    "downgrade_allowed": True
}
headers = {
    "wb-key": "<api-key>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {'wb-key': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    upgrade_configuration: {
      activation: {type: 'next_cycle'},
      plan_id: 'Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670',
      unit_configuration: {},
      unit_count_configuration: {},
      upgrade_strategy: 'new_plan',
      discount_id: 'Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670',
      pricing_id: 'Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670'
    },
    downgrade_allowed: true
  })
};

fetch('http://127.0.0.1:8080/v1/c/contract/{contract_id}/upgrade', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_PORT => "8080",
  CURLOPT_URL => "http://127.0.0.1:8080/v1/c/contract/{contract_id}/upgrade",
  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([
    'upgrade_configuration' => [
        'activation' => [
                'type' => 'next_cycle'
        ],
        'plan_id' => 'Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670',
        'unit_configuration' => [
                
        ],
        'unit_count_configuration' => [
                
        ],
        'upgrade_strategy' => 'new_plan',
        'discount_id' => 'Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670',
        'pricing_id' => 'Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670'
    ],
    'downgrade_allowed' => true
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "wb-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 := "http://127.0.0.1:8080/v1/c/contract/{contract_id}/upgrade"

	payload := strings.NewReader("{\n  \"upgrade_configuration\": {\n    \"activation\": {\n      \"type\": \"next_cycle\"\n    },\n    \"plan_id\": \"Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670\",\n    \"unit_configuration\": {},\n    \"unit_count_configuration\": {},\n    \"upgrade_strategy\": \"new_plan\",\n    \"discount_id\": \"Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670\",\n    \"pricing_id\": \"Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670\"\n  },\n  \"downgrade_allowed\": true\n}")

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

	req.Header.Add("wb-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("http://127.0.0.1:8080/v1/c/contract/{contract_id}/upgrade")
  .header("wb-key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"upgrade_configuration\": {\n    \"activation\": {\n      \"type\": \"next_cycle\"\n    },\n    \"plan_id\": \"Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670\",\n    \"unit_configuration\": {},\n    \"unit_count_configuration\": {},\n    \"upgrade_strategy\": \"new_plan\",\n    \"discount_id\": \"Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670\",\n    \"pricing_id\": \"Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670\"\n  },\n  \"downgrade_allowed\": true\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("http://127.0.0.1:8080/v1/c/contract/{contract_id}/upgrade")

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

request = Net::HTTP::Post.new(url)
request["wb-key"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"upgrade_configuration\": {\n    \"activation\": {\n      \"type\": \"next_cycle\"\n    },\n    \"plan_id\": \"Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670\",\n    \"unit_configuration\": {},\n    \"unit_count_configuration\": {},\n    \"upgrade_strategy\": \"new_plan\",\n    \"discount_id\": \"Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670\",\n    \"pricing_id\": \"Cust_c40bea18-c0c9-44b1-bd0c-43f5283e1670\"\n  },\n  \"downgrade_allowed\": true\n}"

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

"Cont_cc871a3a-2b38-4689-a32d-14bf2e62b1ae"