code: public Widget addWidget(String widgetId, int columnId) {
      if (columnId < 1) {
        throw new IllegalArgumentException("Widget column starts with 1");
      }
  
      Widget widget = new Widget(widgetId);
      widgetsByColumn.put(columnId, widget);
      return widget;
    }
docs: Add a widget with the given parameters, and return the newly created {@link Widget} object if one wants to add parameters to it.
  
  <p>The widget ids are listed by the web service /api/widgets
  
  @param widgetId id of an existing widget
  @param columnId column starts with 1. The widget is ignored if the column id does not match the layout.