private static void registerUDF() {
    try (Connection connection = EnvFactory.getEnv().getConnection();
        Statement statement = connection.createStatement()) {
      statement.execute(
          "create function window_start_end as 'org.apache.iotdb.db.query.udf.example.WindowStartEnd'");
    } catch (SQLException throwable) {
      fail(throwable.getMessage());
    }
  }
Test for SessionWindow, StateWindow and UserDefinedWindow.
integration-test/src/test/java/org/apache/iotdb/db/it/udf/IoTDBUDFOtherWindowQueryIT.java