refactor(o11y): simplify GoldenSignalsMetricsRecorder to act as a no-op

Removed repetitive check for LibraryMetadata and artifactName from GoldenSignalsMetricsTracerFactory#withContext. Instead, GoldenSignalsMetricsRecorder gracefully handles missing metadata by acting as a no-op instead of creating an underlying OpenTelemetry instrument.

Author: blakeli0

sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/tracing/GoldenSignalsMetricsRecorder.java

@@ -51,12 +51,16 @@ class GoldenSignalsMetricsRecorder {
       Arrays.asList(
           0.0, 0.0001, 0.0005, 0.0010, 0.005, 0.010, 0.050, 0.100, 0.5, 1.0, 5.0, 10.0, 60.0, 300.0,
           900.0, 3600.0);
-  final DoubleHistogram clientRequestDurationRecorder;
+  @javax.annotation.Nullable final DoubleHistogram clientRequestDurationRecorder;
 
   GoldenSignalsMetricsRecorder(
       OpenTelemetry openTelemetry, com.google.api.gax.rpc.LibraryMetadata libraryMetadata) {
     String libraryName =
-        libraryMetadata.artifactName() != null ? libraryMetadata.artifactName() : "";
+        libraryMetadata != null && libraryMetadata.artifactName() != null ? libraryMetadata.artifactName() : "";
+    if (libraryName.isEmpty()) {
+      this.clientRequestDurationRecorder = null;
+      return;
+    }
     io.opentelemetry.api.metrics.MeterBuilder meterBuilder =
         openTelemetry.meterBuilder(libraryName);
     String libraryVersion = libraryMetadata.version();
@@ -75,7 +79,9 @@ class GoldenSignalsMetricsRecorder {
   }
 
   void recordOperationLatency(double operationLatency, Map<String, Object> attributes) {
-    clientRequestDurationRecorder.record(
-        operationLatency, ObservabilityUtils.toOtelAttributes(attributes));
+    if (clientRequestDurationRecorder != null) {
+      clientRequestDurationRecorder.record(
+          operationLatency, ObservabilityUtils.toOtelAttributes(attributes));
+    }
   }
 }

sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/tracing/GoldenSignalsMetricsTracerFactory.java

@@ -79,10 +79,6 @@ public ApiTracerFactory withContext(ApiTracerContext context) {
     if (context == null) {
       return new BaseApiTracerFactory();
     }
-    LibraryMetadata metadata = context.libraryMetadata();
-    if (metadata == null || metadata.isEmpty() || Strings.isNullOrEmpty(metadata.artifactName())) {
-      return new BaseApiTracerFactory();
-    }
     this.clientLevelTracerContext = context;
     this.metricsRecorder =
         new GoldenSignalsMetricsRecorder(