Add tracing for microprofile-rest-client

[pavolloffay]

Add tracing for https://github.com/eclipse/microprofile-rest-client. Tracing metadata like tags/logs should be the same as for JAX-RS client.

We need to figure out how this cross-spec specification should be handled. Should it be added here or in microprofile-rest-client? I would vote to add it here.

cc @pilhuhn @kwsutter

A pointer to rest-client issue allowing tracing integration eclipse/microprofile-rest-client#35 (comment).

[kenfinnigan]

There has been some discussion in the past around spec integration and the need for a MP level spec to cover those interactions.

Doing so would also provide for a MP level TCK to verify such behavior

[pavolloffay]

Is there any timeline to add MP level spec?

My main concern about adding microprofile-rest-client here is that this spec shouldn't probably directly depend on the microprofile-rest-client. What if a vendor does not support mp-rest-client but it wants to use tracing only for jax-rs?

[kenfinnigan]

I don't think there is, but we can raise it again today

[andymc12]

@pavolloffay It should be possible to add Open Tracing providers to the MP Rest Client with only a compile-time dependency on microprofile-rest-client. You would need the compile-time dependency in order to build the RestClientBuilderListener implementation class (which could then register the Open Tracing provider(s)), but that class would only be loaded by the MP Rest Client implementation at runtime - so there is no need for a runtime dependency.