Vertx http client 3 instrumentation populating relative URL in http.url

[anuraaga]

We currently populating the confusingly named relative URI field as http.url

https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/main/instrumentation/vertx-http-client/vertx-http-client-3.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/vertx/v3_0/client/Vertx3HttpAttributesExtractor.java#L17

We hadn't noticed it because this line is incorrect.

https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/main/instrumentation/vertx-http-client/vertx-http-client-3.0/javaagent/src/test/groovy/client/VertxHttpClientTest.groovy#L34

It should be httpClient.requestAbs(HttpMethod.valueOf(method), "$uri")

It seems like Jetty and older versions of Armeria handled an absolute URL as a path leniently in a way that worked. When trying to update Armeria I found this test failing with HTTP 400. It did make clear that when using the methods correctly, the instrumentation populates a relative path into that attribute.

Unfortunately there doesn't seem to be a way to access hostname publicly. Should we instrument the constructor to store it in a virtual field? Or any other tips appreciated.