public long getEndTime() {
    return endTime;
  }
The parameter of `GROUP BY TIME`.

<p>Remember: interval and slidingStep is always in timestamp unit before transforming to
timeRangeIterator even if it's by month unit.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/planner/plan/parameter/GroupByTimeParameter.java