Add custom grid column with group_concat

I want to get all the inventory stock for each source in the product grid.

So far, I’ve added the column, with success, by adding to Vendor/Module/etc/adminhtml/di.xml:

 
     
         
            VendorModuleUiDataProviderProductAddStockFieldToCollection 
        
     
 

Also created the file and confirmed it’s being executed VendorModuleUiDataProviderProductAddStockFieldToCollection.php with:

< ?php 
namespace VendorModuleUiDataProviderProduct; 
class AddStockFieldToCollection implements MagentoUiDataProviderAddFieldToCollectionInterface 
{ 
    public function addField(MagentoFrameworkDataCollection $collection, $field, $alias = null) 
    {
        /* code */
    }
}

In addField, i was able to joinField or joinTable (but only a single one). I want to group_concat inventory source code with corresponding quantity.

I tried using vendormagentomodule-catalogUiComponentListingColumnsWebsites.php as a reference, but this only uses website name.