code: public static DoublesColumn create(ColumnarDoubles column, ImmutableBitmap nullValueBitmap)
    {
      if (nullValueBitmap.isEmpty()) {
        return new DoublesColumn(column);
      } else {
        return new DoublesColumnWithNulls(column, nullValueBitmap);
      }
    }
docs: Factory method to create DoublesColumn.