Rename BaggageKeyPredicate to Filter (#5809)

`baggagetrace.BaggageKeyPredicate` is overly verbose. Given this type is
used as a filter, rename it to match its functionality.

CHANGELOG.md

@@ -45,6 +45,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Improve performance of `go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc` with the usage of `WithAttributeSet()` instead of `WithAttribute()`. (#5664)
 - 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)
 
 ## [1.27.0/0.52.0/0.21.0/0.7.0/0.2.0] - 2024-05-21
 

processors/baggage/baggagetrace/processor.go

@@ -11,15 +11,16 @@ import (
 	"go.opentelemetry.io/otel/sdk/trace"
 )
 
-// BaggageKeyPredicate is a function that returns true if the baggage key should be added to the span.
-type BaggageKeyPredicate func(baggageKey string) bool
+// Filter returns true if the baggage member with key should be added to a
+// span.
+type Filter func(key string) bool
 
-// AllowAllBaggageKeys is a BaggageKeyPredicate that allows all baggage keys.
-var AllowAllBaggageKeys = func(string) bool { return true }
+// 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.
 type SpanProcessor struct {
-	baggageKeyPredicate BaggageKeyPredicate
+	filter Filter
 }
 
 var _ trace.SpanProcessor = (*SpanProcessor)(nil)
@@ -28,17 +29,17 @@ var _ trace.SpanProcessor = (*SpanProcessor)(nil)
 //
 // 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 predicate function is used to filter which baggage keys are added to the span.
-func New(baggageKeyPredicate BaggageKeyPredicate) trace.SpanProcessor {
+// The passed filter determines which baggage members are added to the span.
+func New(filter Filter) trace.SpanProcessor {
 	return &SpanProcessor{
-		baggageKeyPredicate: baggageKeyPredicate,
+		filter: filter,
 	}
 }
 
 // OnStart is called when a span is started and adds span attributes for baggage contents.
 func (processor SpanProcessor) OnStart(ctx context.Context, span trace.ReadWriteSpan) {
 	for _, entry := range otelbaggage.FromContext(ctx).Members() {
-		if processor.baggageKeyPredicate(entry.Key()) {
+		if processor.filter(entry.Key()) {
 			span.SetAttributes(attribute.String(entry.Key(), entry.Value()))
 		}
 	}