title: Get Jenkins credentials usage list - groovy script
body: <p>As a Jenkins admin, i would like to clean unused credentials from the Jenkins. Is it possible to run some groovy script in the Script Console so the output will be:</p>
  
  <pre><code>CRED: job1, job2 ...
  </code></pre>
  
  <p>Or some other readable format so we could see stored creds usage.</p>