@BinderThread
  private void handleStartJobRequest(JobParameters job, IJobCallback callback) {
    backgroundExecutor.execute(UnitOfWork.handleStartJobRequest(this, job, callback));
  }
Asks the {@code job} to start running. Calls {@link #onStartJob} on the main thread. Once
complete, the {@code callback} will be used to send the result back.
jobdispatcher/src/main/java/com/firebase/jobdispatcher/JobService.java