Return SpanProcessor ptr not trace.SpanProcessor from `baggagetra…

…ce.New` (#5810)

Return the concrete type so user wanting underlying type do not need to
make a type assertion.

CHANGELOG.md

@@ -46,6 +46,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Improve performance of `go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp` with the usage of `WithAttributeSet()` instead of `WithAttribute()`. (#5664)
 - Update `go.opentelemetry.io/contrib/config` to latest released configuration schema which introduces breaking changes where `Attributes` is now a `map[string]interface{}`. (#5758)
 - Rename `BaggageKeyPredicate` to `Filter` in `go.opentelemetry.io/contrib/processors/baggage/baggagetrace`. (#5809)
+- Return `*SpanProcessor` from `"go.opentelemetry.io/contrib/processors/baggage/baggagetrace".New` instead of the `trace.SpanProcessor` interface. (#5810)
 
 ## [1.27.0/0.52.0/0.21.0/0.7.0/0.2.0] - 2024-05-21
 

processors/baggage/baggagetrace/processor.go

@@ -18,19 +18,20 @@ type Filter func(key string) bool
 // AllowAllBaggageKeys allows all baggage members to be added to a span.
 var AllowAllBaggageKeys Filter = func(string) bool { return true }
 
-// SpanProcessor is a processing pipeline for spans in the trace signal.
+// SpanProcessor is a [trace.SpanProcessor] implementation that adds baggage
+// members onto a span as attributes.
 type SpanProcessor struct {
 	filter Filter
 }
 
 var _ trace.SpanProcessor = (*SpanProcessor)(nil)
 
-// New returns a new SpanProcessor.
+// New returns a new [SpanProcessor].
 //
 // The Baggage span processor duplicates onto a span the attributes found
 // in Baggage in the parent context at the moment the span is started.
 // The passed filter determines which baggage members are added to the span.
-func New(filter Filter) trace.SpanProcessor {
+func New(filter Filter) *SpanProcessor {
 	return &SpanProcessor{
 		filter: filter,
 	}