trace

opentrace: https://github.com/opentracing-contrib/opentracing-specification-zh/blob/master/semantic_conventions.md opentelemetry: https://github.com/open-telemetry/opentelemetry-specification/tree/main/specification/trace/semantic_conventions tracecontext: https://www.w3.org/TR/trace-context/ nginx otel:https://github.com/open-telemetry/opentelemetry-cpp-contrib/tree/main/instrumentation/nginx