docs: public static Job[] all() {
      List list = UKV.get(LIST);
      Job[] jobs = new Job[list==null?0:list._jobs.length];
      int j=0;
      for( int i=0; i<jobs.length; i++ ) {
        Job job = UKV.get(list._jobs[i]);
        if( job != null ) jobs[j++] = job;
      }
      if( j<jobs.length ) jobs = Arrays.copyOf(jobs,j);
      return jobs;
    }