Web Designer. How to concatenate text from multiple rows of collection into a single property ShoppingCartItem?

Hello! 

1IM 8.1.2. 

I filled custom collection values and I need concatenate text from multiple rows of the collection into a single property ShoppingCartItem.

For example 

Custom collection:

Name

Peter

Alex

Ivan

Result: 

ShoppingCartItem.CustomProperty01 = Peter,Alex,Ivan

 

How can I do that?