public List<PlanNode> visit(PlanNode node, DistributionPlanContext context) {
    return node.accept(this, context);
  }
This method is used for rewriting second step AggregationNode like GroupByLevelNode,
GroupByTagNode and SlidingWindowAggregationNode, so the first step AggregationNode's step will
be {@link AggregationStep#PARTIAL}
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/planner/distribution/SourceRewriter.java