title: Caching in UrlFetchApp
body: <p>In Google App Script I'm using <code>UrlFetchApp()</code> to bring in some code served from an outside host.  I make changes to the code served on that host but these aren't appearing in the code run by script.</p>
  
  <p>My server logs show that the desired is sometimes requested (and served) but it isn't showing up in the script.</p>
  
  <p>I'm using <code>optAdvancedArgs</code> in my UrlFetchApp call, passing in <code>{"headers" : {"Cache-Control": "no-cache"}</code> </p>
  
  <p>but this isn't helping.</p>
  
  <p>Is there some kind of caching of resources obtained by <code>UrlFetchApp()</code>, and if so how can I turn it off?</p>