code: public void setDeliveryForecastSource(com.google.api.ads.admanager.axis.v201902.DeliveryForecastSource deliveryForecastSource) {
          this.deliveryForecastSource = deliveryForecastSource;
      }
docs: Sets the deliveryForecastSource value for this LineItemSummary.
  
  @param deliveryForecastSource   * Strategy for choosing forecasted traffic shapes to pace line
  items. This field is optional and
  defaults to {@link DeliveryForecastSource#HISTORICAL}.