Make client.address sampling relevant on HTTP server spans

CHANGELOG.md

@@ -36,6 +36,8 @@ release.
   ([#449](https://github.com/open-telemetry/semantic-conventions/pull/449))
 - Change `user_agent.original` from recommended to opt-in on HTTP client spans.
   ([#468](https://github.com/open-telemetry/semantic-conventions/pull/468))
+- Make `client.address` sampling relevant on HTTP server spans.
+  ([#469](https://github.com/open-telemetry/semantic-conventions/pull/469))
 
 ### Features
 

docs/http/http-spans.md

@@ -373,6 +373,7 @@ SHOULD include the [application root](/docs/http/http-spans.md#http-server-defin
 
 Following attributes MUST be provided **at span creation time** (when provided at all), so they can be considered for sampling decisions:
 
+* [`client.address`](../general/attributes.md)
 * [`server.address`](../general/attributes.md)
 * [`server.port`](../general/attributes.md)
 * [`url.path`](../attributes-registry/url.md)

model/trace/http.yaml

@@ -66,6 +66,7 @@ groups:
         requirement_level: opt_in
         brief: Local socket port. Useful in case of a multi-port host.
       - ref: client.address
+        sampling_relevant: true
         note: >
             The IP address of the original client behind all proxies, if
             known (e.g. from [Forwarded#for](https://developer.mozilla.org/docs/Web/HTTP/Headers/Forwarded#for),