I want to add stock information to returned cart item

Hi, I’m developing headless website and i need to validate cart items changing qty (changing the quantity in cart). So i need to add property stock status and stock quantity to returned cart item. I found this filter in documentation on github “cocart_cart_contents”, using which I’m supposed to do this. But nothing changes. Can you help me and say what i have to do?
“https://github.com/co-cart/cocart-api-reference-docs/blob/master/source/includes/cocart-v2/_filters.md” – this is the link where i looked for filters