I'm using Storefront API and for now i'm testing it in Postman. I know how to get products from collection but now, i want to filter products in collection and I don't know how can I do that. I've searched web and I found this article in documentation of Shopify API but it doesn't work for me. Here is a picture where I show how my POSTMAN query looks like and what error I get. If someone knows what I'm doing wrong, please tell me, I would be very grateful.