The URL used when HTTP requests are performed is defined statically with the url_prefix passed to the constructor of JsonHttpApiClient together with the path property in JsonHttpApiFunction.
For applications that require dynamic URLs there is no way to rewrite the URL. Let's add a mechanism that allows API users to apply custom URL reqriting rules by adding a reqrite_url method to JsonHttpApiFunction. API users may then overload this method with a custom implementation as needed.
