Transforming Retry-After Headers in Azure APIM: A Step-by-Step Guide

Noted the Incorrect syntax on `on-error` Should be something like below,

<on-error>
   <choose>
      <!-- Note: Need to be case-sensitive: ratelimitexceeded vs RateLimitExceeded -->
      <!-- Or better string.Equals(context.LastError.Reason, "ratelimitexceeded", System.StringComparison.OrdinalIgnoreCase)) -->
     <when condition="@(context.LastError.Reason == "RateLimitExceeded")">
       <set-header name="Retry-After" exists-action="override">
         <value>@(DateTime.UtcNow.AddSeconds(context.Variables.GetValueOrDefault<int>("retryAfter")).ToString("o"))</int></value>
       </set-header>
     </when>
  </choose>
  <base>
</on-error>