/**
  * 
  * By default {@link AbstractQueuedJob} will only queue 1 "identical" job at 
  * a time, so an implementation of this method is necessary becuase we need 
  * to fire-off multiple jobs for processing a different chunk of objects.
  * 
  * See the QueuedJobs' wiki for more info:
  * https://github.com/silverstripe-australia/silverstripe-queuedjobs/wiki/Defining-queued-jobs
  * 
  * @return string
  */
 public function getSignature()
 {
     parent::getSignature();
     return $this->randomSignature();
 }
 public function getSignature()
 {
     return parent::getSignature();
 }