declarative config: add declaravite config bridge, gcp auth, span stacktrace

[zeitlinger]

Blocked by open-telemetry/opentelemetry-configuration#257 for GCP auth

Fixes #2012
Fixes #2028

[otelbot-java-contrib]

🔧 The result from spotlessApply was committed to the PR branch.

[zeitlinger]

notes from discussion with @jaydeluca

[zeitlinger]

the bridge is also part of open-telemetry/opentelemetry-java-instrumentation#14184 - once it's reviewed there it will be updated here

but that can also be done after this PR is merged

[psx95]

Thanks a lot for the the PR @zeitlinger ! 💯

I left some suggestions and a question. Let me know your thoughts on them.

[psx95]

Question: The addAuth method seems to add a fixed key-value pair to a list of headers associated with the span exporter / metric exporter.

In this case, I don't see how a token refresh for the auth headers work or am I missing something here ?

[zeitlinger]

great catch - I missed the refresh part completely - I have to check how this is even supposed to work

[psx95]

An additional header that is important to check here is the auth header.
[name=Authorization, value=bearer fake-credential-token].

Sample setup:

mockedRequestMetadata =
        ImmutableMap.of(
              "Authorization",
              Collections.singletonList("Bearer fake-access-token"),
              QUOTA_USER_PROJECT_HEADER,
              Collections.singletonList("qp"));

Mockito.when(mockedGoogleCredentials.getRequestMetadata()).thenReturn(mockedRequestMetadata);

PS: I can update the testing later as well.