title: Cron expression two times per month
body: <p>The following cron expression :</p>
  
  <pre><code>&lt;cron-expression&gt;0 0 6 1 1/1 ? *&lt;/cron-expression&gt;
  </code></pre>
  
  <p>will run 06:00 AM on the 1-st day every month. But how to set this cron expression to run on the 1st day, and on the 16th day of every month?</p>