How to return xml in GoogleShopping plugin?

Litium version: 7

Hi,
In Litium 7, I am using Litium.Studio.AddOns.PriceAgents
in GoogleShopping plugin I want to return response as xml,
I tried setting
public string ContentType
{
get { return “text/xml”; }
}
also tried application/xml, but I am getting the below error in response,

This page contains the following errors:
error on line 1 at column 1: Document is empty
Below is a rendering of the page up to the first error.

If any one has done this, please let me know.

or should I implement a custom logic in Render method.

The default implementation of the Google Shopping feed in Litium 7 generates a XML document, have you made a custom implementation to suit a specific need?
https://docs.litium.com/documentation/litium-documentation/products/price-agents/google-shopping

To create an own price agent feed you need to implement all the properties and methods on the Litium.Web.Products.PriceAgents.IPriceAgent interface.

Not sure if you building your own Google Shopping Feed or what you are doing. Litium is pre-build with a Google Shopping Feed that can be used out of the box.