Example to add a widget manually by overwriting this method in your report:
$widgetsList->addWidgetConfig($factory->createWidget());
If you want to have the name and the order of the widget differently to the name and order of the report you can
do the following:
$widgetsList->addWidgetConfig($factory->createWidget()->setName('Custom')->setOrder(5));
If you want to add a widget to any container defined by your plugin or by another plugin you can do
this:
$widgetsList->addToContainerWidget($containerId = 'Products', $factory->createWidget());