code: private static water.Job resolveJob(JobId request) {
      String strId = request.getJobId();
      Value val = DKV.get(Key.make(strId));
      if (val == null) {
        throw new IllegalArgumentException("Job " + strId + " not found in the DKV");
      }
      Iced iced = val.get();
      if (iced instanceof Job) {
        return (water.Job) iced;
      } else {
        throw new IllegalArgumentException("Id " + strId + " does not reference a Job but a " + iced.getClass());
      }
    }
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