private ScheduledQuery composeOverlayObject(ScheduledQuery ...overlays) {
    ScheduledQuery ret = new ScheduledQuery();
    _Fields[] q = ScheduledQuery._Fields.values();
    for (_Fields field : q) {
      for (ScheduledQuery o : overlays) {
        if (o.isSet(field)) {
          ret.setFieldValue(field, o.getFieldValue(field));
          break;
        }
      }
    }
    return ret;
  }
Composes an overlay object.

Output is a flattened view of the input objects.
having the value from the first one which has it defined from the overlays.
ql/src/java/org/apache/hadoop/hive/ql/parse/ScheduledQueryAnalyzer.java