title: Schedule a job in quartz with a set of triggers
body: <p>I am using quartz 2.2 and I want to schedule a job with a set of triggers.
     I plan to use the following method.</p>
  
  <pre><code>void scheduleJobs(Map&lt;JobDetail, Set&lt;? extends Trigger&gt;&gt; triggers, boolean replace)
  </code></pre>
  
  <p>My question is, how do I create a <code>Set</code> that takes in a class that extends <code>Trigger</code>?
  <code>TriggerBuilder</code> returns only the <code>Trigger</code>, but I can't put the same in the set.
  I searched the API but could not find a solution.</p>
  
  <p>Thanks</p>