@Override
  public void check() {
    super.check();
    if (accessStrategy == null) {
      throw new RuntimeException("Access strategy is not set.");
    }
    accessStrategy.check();
  }
Used to specify the strategy for accessing raw query data in UDTF.

@param accessStrategy the specified access strategy. it should be an instance of {@link
    AccessStrategy}.
@return this
@see RowByRowAccessStrategy
@see SlidingTimeWindowAccessStrategy
@see SlidingSizeWindowAccessStrategy
iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/customizer/config/UDTFConfigurations.java