Populate Upstream `url.template` Attribute by Propagating Downstream `http.route` via Response Header

[wl2027]

Is your feature request related to a problem? Please describe.

the low-cardinality url.template is hard to obtain.

Describe the solution you'd like

if the upstream url.template can be deemed equivalent to the downstream http.route, would it be possible to propagate the serverhttp.route as the client url.template via a unified callback hook?

Describe alternatives you've considered

for example, define a specific key via hook component, like HttpServerResponseCustomizer.

Additional context

#14525

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[laurit]

I'm not sure whether we'd want to support this feature. Have you tried implementing it yourself as an agent extension? We'd be open to discussing issues that could prevent you from implementing it yourself. I personally would be more interested in a rule based mechanism that would let users express that when a request is made to http://any.com/foo/bar then the template should be set to /foo/*. Would that work for you?