/**
  * Validates that at least one timeTrigger has been selected, since this is required for a by-time workflow
  * @return bool
  */
 public function validateTimeTrigger()
 {
     if ($this->timeTriggerAttribute == null) {
         $this->addError('timeTriggerAttribute', Zurmo::t('WorkflowsModule', 'At least one time trigger must be selected'));
         return false;
     } else {
         return parent::validateTimeTrigger();
     }
 }