First of all your api is /api/public/categories but you are trying to request api/public/products

When you build your app and sending a get request from a browser like below you have to get success response.

The parameter name that you request must match the name field in the @RequestParam annotation.

Remove empty character inside of name field

@RequestParam(name = "Page_size", defaultValue = Appconstants.PAGE_SIZE,required = false) Integer pgsize,