Get quote products from CRM

Get quote products from CRM

Hi! I try to get quote's products with such code:
  1. response = zoho.crm.getRecordById("Quotes", <quote_id>);
and then it's not possible to access field "product" as a list, because it's a String. Such code:
  1. products = response.get("product").toList();
is not working, it simply breaks a string into parts by commas.
How can I access products correctly?
UPD: And how then to update existing products? If I pass a map with products to zoho.crm.updateRecord it will append this products to the existing one.
Thanks in advance!