curl --request POST \
  --url https://virtserver.swaggerhub.com/BangoProducts/MerchantInterface_Server_API/1.1.0/v1/echo/{echoRequestId} \
  --header 'Authorization: Basic <encoded-value>'

const options = {method: 'POST', headers: {Authorization: 'Basic <encoded-value>'}};

fetch('https://virtserver.swaggerhub.com/BangoProducts/MerchantInterface_Server_API/1.1.0/v1/echo/{echoRequestId}', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://virtserver.swaggerhub.com/BangoProducts/MerchantInterface_Server_API/1.1.0/v1/echo/{echoRequestId}"

headers = {"Authorization": "Basic <encoded-value>"}

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

print(response.text)

{
  "responseCode": "OK",
  "responseMessage": "Success",
  "echo": "a25100b8-4e0c-4e37-b921-cac9cb1e930f"
}

{
  "responseCode": "BAD_REQUEST",
  "responseMessage": "Invalid request"
}

{
  "responseCode": "UNAUTHORIZED",
  "responseMessage": "You have not provided adequate credentials to access this resource."
}

{
  "responseCode": "TOO_MANY_REQUESTS",
  "responseMessage": "Request limit reached. Please try again later"
}

{
  "responseCode": "INTERNAL_ERROR",
  "responseMessage": "The server encountered an unexpected condition which prevented it from fulfilling the request"
}

{
  "responseCode": "SERVICE_UNAVAILABLE",
  "responseMessage": "The server is undergoing maintenance and is not available. Please, try again later"
}