@Override
  public void check() {
    if (delta < 0) {
      throw new RuntimeException(
          String.format("Parameter delta(%f) should be positive or equal to 0.", delta));
    }
    if (displayWindowEnd < displayWindowBegin) {
      throw new RuntimeException(
          String.format(
              "displayWindowEnd(%d) < displayWindowBegin(%d)",
              displayWindowEnd, displayWindowBegin));
    }
  }
Display window begin will be set to the same as the minimum timestamp of the query result set,
and display window end will be set to the same as the maximum timestamp of the query result
set. delta default equals 0.
iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/customizer/strategy/StateWindowAccessStrategy.java