Make the new feature experimental

Author: dylanahsmith

opentelemetry-appender-tracing/CHANGELOG.md

@@ -3,7 +3,7 @@
 ## vNext
 
 - Bump msrv to 1.75.0.
-- Include trace_id & span_id when logging from inside a tracing span
+- New experimental feature to use trace\_id & span\_id from spans created through the tracing crate (experimental-use-tracing-span-context) [#2438](https://github.com/open-telemetry/opentelemetry-rust/pull/2438)
 
 
 ## 0.27.0

opentelemetry-appender-tracing/Cargo.toml

@@ -34,10 +34,9 @@ tokio = { workspace = true, features = ["full"]}
 pprof = { version = "0.13", features = ["flamegraph", "criterion"] }
 
 [features]
-default = ["tracing"]
 experimental_metadata_attributes = ["dep:tracing-log"]
 spec_unstable_logs_enabled = ["opentelemetry/spec_unstable_logs_enabled"]
-tracing = ["tracing-opentelemetry"]
+experimental-use-tracing-span-context = ["tracing-opentelemetry"]
 
 
 [[bench]]

opentelemetry-appender-tracing/src/layer.rs

@@ -180,7 +180,7 @@ where
         // Visit fields.
         event.record(&mut visitor);
 
-        #[cfg(feature = "tracing")]
+        #[cfg(feature = "experimental-use-tracing-span-context")]
         if let Some(span) = _ctx.event_span(event) {
             use tracing_opentelemetry::OtelData;
             let opt_span_id = span
@@ -511,7 +511,7 @@ mod tests {
         }
     }
 
-    #[cfg(feature = "tracing")]
+    #[cfg(feature = "experimental-use-tracing-span-context")]
     #[test]
     fn tracing_appender_inside_tracing_crate_context() {
         use opentelemetry_sdk::testing::trace::InMemorySpanExporterBuilder;