title: Fetch users in workflow definition
body: <p>I am using Liferay 6.1.1CE with kaleo workflow.</p>
  
  <p>I am created a new workflow definition,by editing singlelevel workflow.xml.</p>
  
  <p>In my workflow definition,i had add a new transition "reference" and a task for the same.</p>
  
  <p>In my reference task,i have to select a user from all users to send the reference.</p>
  
  <p>How can i fetch the users..? Is it possible?</p>