title: jenkins extended parameter plugin groovy script
body: <p>The <a href="https://wiki.jenkins-ci.org/display/JENKINS/Extended+Choice+Parameter+plugin">website for the plugin</a> says that you can create a groovy script to run to determine the parameter list.</p>
  
  <p>how is this resolved though? The instructions don't say anything. </p>
  
  <ol>
  <li>In what context is the script run?</li>
  <li>What am i supposed to return from the script?</li>
  <li>What directory is the cwd of the script? is it the environment variable WORKSPACE?</li>
  <li>there is an extra field called <code>variable bindings</code>. How is this used?</li>
  </ol>