curl --request POST \
  --url https://api.sandbox.lead.bank/v2/user_accounts/{user_account_id}/entity_relationships/batch \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'Idempotency-Key: <idempotency-key>' \
  --data '
{
  "entity_ids": [
    "entity_8kL9jH7gF6dS5aQ4wE3rT2yU1iO",
    "entity_2mN3bV4cX5zL6kwdJ7hG8fD9sA0",
    "entity_1qW2eR3tY4uI5oP6aS7dF8gH9jK",
    "entity_9pLuO8iK7yJ6hT5gR4fE3dD2sS1",
    "entity_5zX4cV3bN2m1qW0eR9tY8uI7oP6"
  ],
  "relationship_type": "authorized_user"
}
'

import requests

url = "https://api.sandbox.lead.bank/v2/user_accounts/{user_account_id}/entity_relationships/batch"

payload = {
    "entity_ids": ["entity_8kL9jH7gF6dS5aQ4wE3rT2yU1iO", "entity_2mN3bV4cX5zL6kwdJ7hG8fD9sA0", "entity_1qW2eR3tY4uI5oP6aS7dF8gH9jK", "entity_9pLuO8iK7yJ6hT5gR4fE3dD2sS1", "entity_5zX4cV3bN2m1qW0eR9tY8uI7oP6"],
    "relationship_type": "authorized_user"
}
headers = {
    "Idempotency-Key": "<idempotency-key>",
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {
    'Idempotency-Key': '<idempotency-key>',
    Authorization: 'Bearer <token>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    entity_ids: [
      'entity_8kL9jH7gF6dS5aQ4wE3rT2yU1iO',
      'entity_2mN3bV4cX5zL6kwdJ7hG8fD9sA0',
      'entity_1qW2eR3tY4uI5oP6aS7dF8gH9jK',
      'entity_9pLuO8iK7yJ6hT5gR4fE3dD2sS1',
      'entity_5zX4cV3bN2m1qW0eR9tY8uI7oP6'
    ],
    relationship_type: 'authorized_user'
  })
};

fetch('https://api.sandbox.lead.bank/v2/user_accounts/{user_account_id}/entity_relationships/batch', 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.sandbox.lead.bank/v2/user_accounts/{user_account_id}/entity_relationships/batch",
  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([
    'entity_ids' => [
        'entity_8kL9jH7gF6dS5aQ4wE3rT2yU1iO',
        'entity_2mN3bV4cX5zL6kwdJ7hG8fD9sA0',
        'entity_1qW2eR3tY4uI5oP6aS7dF8gH9jK',
        'entity_9pLuO8iK7yJ6hT5gR4fE3dD2sS1',
        'entity_5zX4cV3bN2m1qW0eR9tY8uI7oP6'
    ],
    'relationship_type' => 'authorized_user'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json",
    "Idempotency-Key: <idempotency-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://api.sandbox.lead.bank/v2/user_accounts/{user_account_id}/entity_relationships/batch"

	payload := strings.NewReader("{\n  \"entity_ids\": [\n    \"entity_8kL9jH7gF6dS5aQ4wE3rT2yU1iO\",\n    \"entity_2mN3bV4cX5zL6kwdJ7hG8fD9sA0\",\n    \"entity_1qW2eR3tY4uI5oP6aS7dF8gH9jK\",\n    \"entity_9pLuO8iK7yJ6hT5gR4fE3dD2sS1\",\n    \"entity_5zX4cV3bN2m1qW0eR9tY8uI7oP6\"\n  ],\n  \"relationship_type\": \"authorized_user\"\n}")

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

	req.Header.Add("Idempotency-Key", "<idempotency-key>")
	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.sandbox.lead.bank/v2/user_accounts/{user_account_id}/entity_relationships/batch")
  .header("Idempotency-Key", "<idempotency-key>")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"entity_ids\": [\n    \"entity_8kL9jH7gF6dS5aQ4wE3rT2yU1iO\",\n    \"entity_2mN3bV4cX5zL6kwdJ7hG8fD9sA0\",\n    \"entity_1qW2eR3tY4uI5oP6aS7dF8gH9jK\",\n    \"entity_9pLuO8iK7yJ6hT5gR4fE3dD2sS1\",\n    \"entity_5zX4cV3bN2m1qW0eR9tY8uI7oP6\"\n  ],\n  \"relationship_type\": \"authorized_user\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.sandbox.lead.bank/v2/user_accounts/{user_account_id}/entity_relationships/batch")

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

request = Net::HTTP::Post.new(url)
request["Idempotency-Key"] = '<idempotency-key>'
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"entity_ids\": [\n    \"entity_8kL9jH7gF6dS5aQ4wE3rT2yU1iO\",\n    \"entity_2mN3bV4cX5zL6kwdJ7hG8fD9sA0\",\n    \"entity_1qW2eR3tY4uI5oP6aS7dF8gH9jK\",\n    \"entity_9pLuO8iK7yJ6hT5gR4fE3dD2sS1\",\n    \"entity_5zX4cV3bN2m1qW0eR9tY8uI7oP6\"\n  ],\n  \"relationship_type\": \"authorized_user\"\n}"

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

{
  "user_account_id": "user_account_9h8g7f6e5d4c3b2a1z0y9x8w7v6",
  "relationship_type": "authorized_user",
  "entity_ids": [
    "entity_8kL9jH7gF6dS5aQ4wE3rT2yU1iO",
    "entity_2mN3bV4cX5zL6kwdJ7hG8fD9sA0",
    "entity_1qW2eR3tY4uI5oP6aS7dF8gH9jK",
    "entity_9pLuO8iK7yJ6hT5gR4fE3dD2sS1",
    "entity_5zX4cV3bN2m1qW0eR9tY8uI7oP6"
  ]
}

{
  "code": "request_malformed",
  "message": "The request is invalid and cannot be parsed by the server.",
  "errors": [
    {
      "code": "body_malformed",
      "message": "The request body is missing or isn't a JSON object."
    }
  ]
}

{
  "code": "token_invalid",
  "message": "The bearer token is missing, expired, malformed, or invalid."
}

{
  "code": "object_not_found",
  "message": "No object exists at the requested ID, or it is not visible to this caller."
}

{
  "code": "idempotency_key_in_use",
  "message": "A concurrent request using this Idempotency-Key is still in flight."
}

{
  "code": "related_object_invalid",
  "message": "An object referenced in the request doesn't exist or can't be used.",
  "errors": [
    {
      "code": "reference_not_found",
      "message": "Entity entity_8kL9jH7gF6dS5aQ4wE3rT2yU1iO does not exist.",
      "parameters": [
        "entity_ids[0]"
      ]
    }
  ]
}

{
  "code": "rate_limit_exceeded",
  "message": "You have exceeded the rate limit for this endpoint. Retry with backoff."
}

{
  "code": "internal_server_error",
  "message": "Something went wrong on our end. Contact Lead with the Request-Id if this persists."
}

{
  "code": "service_unavailable",
  "message": "The service is temporarily unavailable. Retry after the indicated delay."
}

{
  "code": "gateway_timeout",
  "message": "An upstream system timed out. Retry with backoff."
}