CachableChunkedRefreshJob::getSignature
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
Signature
public function getSignature()
Returns
- string