https://opentelemetry.io/
https://github.com/open-telemetry

https://opentelemetry.io/docs/

https://opentelemetry.io/docs/instrumentation/
https://opentelemetry.io/docs/instrumentation/java/getting-started/

2022
https://apisix.hashnode.dev/end-to-end-tracing-opentelemetry
https://dev.to/apisix/end-to-end-tracing-with-opentelemetry-a17
    https://github.com/nfrankel/opentelemetry-tracing