export ToZipkinSpanModels for use outside this library (#2027)

* export ToZipkinSpanModels for use outside this library

* Update CHANGELOG.md

CHANGELOG.md

@@ -14,6 +14,8 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ### Changed
 
+- The `SpanModels` function is now exported from the `go.opentelemetry.io/otel/exporters/zipkin` package to convert OpenTelemetry spans into Zipkin model spans. (#2027)
+
 ### Deprecated
 
 ### Removed

exporters/zipkin/model.go

@@ -51,7 +51,9 @@ func init() {
 	}
 }
 
-func toZipkinSpanModels(batch []tracesdk.ReadOnlySpan) []zkmodel.SpanModel {
+// SpanModels converts OpenTelemetry spans into Zipkin model spans.
+// This is used for exporting to Zipkin compatible tracing services.
+func SpanModels(batch []tracesdk.ReadOnlySpan) []zkmodel.SpanModel {
 	models := make([]zkmodel.SpanModel, 0, len(batch))
 	for _, data := range batch {
 		models = append(models, toZipkinSpanModel(data))

exporters/zipkin/model_test.go

@@ -715,7 +715,7 @@ func TestModelConversion(t *testing.T) {
 			Tags: nil, // should be omitted
 		},
 	}
-	gottenOutputBatch := toZipkinSpanModels(inputBatch)
+	gottenOutputBatch := SpanModels(inputBatch)
 	require.Equal(t, expectedOutputBatch, gottenOutputBatch)
 }
 

exporters/zipkin/zipkin.go

@@ -126,7 +126,7 @@ func (e *Exporter) ExportSpans(ctx context.Context, spans []sdktrace.ReadOnlySpa
 		e.logf("no spans to export")
 		return nil
 	}
-	models := toZipkinSpanModels(spans)
+	models := SpanModels(spans)
 	body, err := json.Marshal(models)
 	if err != nil {
 		return e.errf("failed to serialize zipkin models to JSON: %v", err)