@Override
  public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations)
      throws Exception {
    configurations.setAccessStrategy(new RowByRowAccessStrategy()).setOutputDataType(Type.DOUBLE);
  }
calculate the integral or the area under the curve of input series $unit$ is the time scale for
the area calculation, chosen from 1s(second, default), 1m(minute), 1h(hour), 1d(day).
library-udf/src/main/java/org/apache/iotdb/library/dprofile/UDAFIntegralAvg.java