Validate if passed URL uses HTTP or HTTPS schema or there's no indication that any type of schema is used altogether.
This method expects URL decoded value as input. It is safe to pass Struts' action parameter which is URL decoded and trimmed.
returnUrl - URL decoded value of returnUrl query param
Given an URL which may:
- include scheme,host and optionally port
- start directly with context
- start with an arbitrary path under a context
this method returns the path under context.
It should not be used for security purposes, because it operates on best effort basis - including returning
the URL without modifications if context is not found .