@Override
  public void setInputExpressions(List<Expression> inputExpressions) {
    this.inputExpressions = inputExpressions;
    initGroupedInputExpressions();
  }
For an aggregate function that takes two inputs, the inputExpressions may be like
[root.sg.d1.s1, root.sg.d1.s2, root.sg.d2.s1, root.sg.d2.s2]. The inputExpressions is a
one-dimensional List, but it is split by expressionNumOfOneInput. The split result is stored in
groupedInputExpressions So the returned map of this method is : <"root.sg.d1.s1,
root.sg.d1.s2", [root.sg.d1.s1, root.sg.d1.s2]> <"root.sg.d2.s1, root.sg.d2.s2",
[root.sg.d2.s1, root.sg.d2.s2]>
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/planner/plan/parameter/CrossSeriesAggregationDescriptor.java