Unable to populate destination.* for custom span

[tobiasstadler]

Is your feature request related to a problem?

We are using a hardware security module (hsm) for doing some crypto stuff. The communication is done via java.net.Socket. Currently I use ElasticApm.currentSpan().startSpan("external", ...) to create a span for the communication. But the hsm is not listed in the dependencies section of the services overview page in the APM app in Kibana.

Describe the solution you'd like

I would like to set destination ip/port and destination service name/resource/type for my custom span.

Describe alternatives you've considered

I could use reflection or write a plugin and use co.elastic.apm.agent.impl.transaction.Span#getContext to set the fields, but this looks too over engineered to me.

[felixbarny]

Closing as duplicate of #1699
This is currently blocked on a pending spec change: elastic/apm#436

Feel free to chime in on the discussions there