@Override
  public List<Symbol> getOutputSymbols() {
    return ImmutableList.<Symbol>builder()
        .addAll(leftChild.getOutputSymbols())
        .addAll(rightChild.getOutputSymbols())
        .build();
  }
HACK! Used for error reporting in case this ApplyNode is not supported
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/planner/node/CorrelatedJoinNode.java