title: Open or download URL link in Grails Controller
body: <p>I want to render or download a URL that links to a PDF in a Grails controller method. I'm okay with either opening this is in a new or the same tab, or just downloading it. How is this done in grails?</p>
  
  <p>So far I have:</p>
  
  <pre><code>render(url: "http://test.com/my.pdf")
  </code></pre>
  
  <p>However, I get errors with this and other ways I've tried, such as rendering a response with content. Any clues?</p>