public List<HiveCorrelationInfo> get() {
      if (correlationInfos == null) {
        correlationInfos = new ArrayList<>();
        for (RexNode r : projects) {
          correlationInfos.addAll(CorrelationInfoVisitor.getCorrelationInfos(r));
        }
      }
      return correlationInfos;
    }
CorrelationInfoSupplier allows for a lazy fetch so that the HiveCorrelationInfo
only gets retrieved on demand.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/reloperators/HiveProject.java