SpringBoot URI tag of http.client.requests metric ignores REST template's root URI

If RestTemplate is created with a RestTemplateBuilder with a root URI configured, the URI tag of the http.client.requests metric will not include the root.

Comment From: wilkinsona

Here's a possible fix. Flagging for team attention as the change makes RootUriTemplateHandler's use of the delegate pattern apparent from its public API and I'd like to check that we're all happy with that.

Comment From: philwebb

I don't think it's a big problem to expose the fact that RootUriTemplateHandler uses a delegate, the constructor already implies as much.

I do wonder if we should make the RootUriTemplateHandler responsible for creating a new instance of itself. The fact it calls a bunch of getters then uses the constructor again might be a bit brittle. Perhaps something like this would be better?:

if (delegate instanceof RootUriTemplateHandler) {
    return ((RootUriTemplateHandler) delegate).withHandlerWrapper(CapturingUriTemplateHandler::new);
}

The withHandlerWrapper would take a Function<UriTemplateHandler,UriTemplateHandler>.

Comment From: wilkinsona

I like that. Thanks, @philwebb.