title: Using existing enum in JHipster
body: <p>When generating new Entity in JHipster, is it possible to add an existing enum?</p>
  
  <p>For example java.time.DayOfWeek, currently a new enum file is generated.</p>
  
  <p>Am I missing a flag or an option to generator?</p>
  
  <p>Thank you!</p>