Create or update a "Recipients" node

curl --request POST \
     --url https://api.campaign.episerver.net/rest/{clientId}/transactionalmail/{transactionalMailId}/recipientLists \
     --header 'accept: application/json' \
     --header 'content-type: application/x-www-form-urlencoded' \
     --data 'recipientListIds=array'

var myHeaders = new Headers();
myHeaders.append("accept", "application/json");
myHeaders.append("content-type", "application/x-www-form-urlencoded");

var urlencoded = new URLSearchParams();
urlencoded.append("recipientListIds", "array");

var requestOptions = {
   method: 'POST',
   headers: myHeaders,
   body: urlencoded,
   redirect: 'follow'
};

fetch("https://api.campaign.episerver.net/rest/{clientId}/transactionalmail/{transactionalMailId}/recipientLists", requestOptions)
   .then(response => response.text())
   .then(result => console.log(result))
   .catch(error => console.log('error', error));

require "uri"
require "net/http"

url = URI("https://api.campaign.episerver.net/rest/{clientId}/transactionalmail/{transactionalMailId}/recipientLists")

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

request = Net::HTTP::Post.new(url)
request["accept"] = "application/json"
request["content-type"] = "application/x-www-form-urlencoded"
request.body = "recipientListIds=array"

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

import requests

url = "https://api.campaign.episerver.net/rest/{clientId}/transactionalmail/{transactionalMailId}/recipientLists"

payload = 'recipientListIds=array'
headers = {
   'accept': 'application/json',
   'content-type': 'application/x-www-form-urlencoded'
}

response = requests.request("POST", url, headers=headers, data=payload)

print(response.text)

// The "Recipient" node was updated successfully.
{
  "nodeId": "",
  "successorNodeId": "",
  "recipientListIds": [
    0
  ],
  "links": [
    {
      "uriBuilder": {},
      "rels": [
        ""
      ],
      "rel": "",
      "type": "",
      "params": "",
      "title": "",
      "uri": ""
    }
  ],
  "gridLocation": {
    "x": "",
    "y": ""
  }
}

// The "Recipient" node was created successfully.

// The "Recipient" node could not be found. Ensure that the required parameters such as "campaignId" or "recipientListIds" are correct and the "Recipients" node exists.