docs: Container toEfficientContainer() {
      int sizeAsRunContainer = RunContainer.serializedSizeInBytes(this.nbrruns);
      int sizeAsBitmapContainer = BitmapContainer.serializedSizeInBytes(0);
      int card = this.getCardinality();
      int sizeAsArrayContainer = ArrayContainer.serializedSizeInBytes(card);
      if (sizeAsRunContainer <= Math.min(sizeAsBitmapContainer, sizeAsArrayContainer)) {
        return this;
      }
      return toBitmapOrArrayContainer(card);
    }