Not able to add custom fields data in zoho books contacts with deluge script

Not able to add custom fields data in zoho books contacts with deluge script

Hey here i have written the deluge script in zoho crm to send data of contacts in zoho books but only contact_name is getting entered in zoho data
vendor_data = Map();
vendor_data.put("contact_name",beneficiary_record.get("Name"));
vendor_data.put("email",beneficiary_record.get("Email"));
vendor_data.put("phone",beneficiary_record.get("Phone"));
vendor_data.put("contact_type","vendor");
vendor_data.put("cf_customer_id","recordId");
l = list();
m = Map();
m.put("index", 1);
m.put("value", "NEW ID CONETENT");
l.add(m);
vendor_data.put("custom_fields",l);
create_vendor_response = zoho.books.createRecord("Contacts",books_org_id,vendor_data,"booksconnection");