How to access the data of a related panel from the controller

Hello a greeting
I have the following form, which is displayed in a popup window

From the controller I access the field data, but I have not found a way to access the panel-related data

In the previous image you can see how from the controller I access the dymmy $_productModel field, but I have tried everything to access the data (which is a grid) of the panel-related panelListSalerOrderLine


You can get the value of panel-related field using field value.
For your field="$productList" it can be accessed like List productList = (List) request.getContext().get("productList");

Thank you