chore: Add implementation for missing classes

Author: lqiu96

java-datastore/google-cloud-datastore/src/main/java/com/google/cloud/datastore/telemetry/MetricsRecorder.java

@@ -92,8 +92,11 @@ static MetricsRecorder getInstance(@Nonnull DatastoreOptions datastoreOptions) {
         && !metricsDisabledViaEnv) {
       try {
         OpenTelemetry builtInOtel =
-            BuiltInMetricsProvider.INSTANCE.getOrCreateOpenTelemetry(
-                datastoreOptions.getProjectId(), datastoreOptions.getCredentials());
+            DatastoreBuiltInMetricsProvider.INSTANCE.getOrCreateOpenTelemetry(
+                datastoreOptions.getProjectId(),
+                datastoreOptions.getCredentials(),
+                null,
+                datastoreOptions.getUniverseDomain());
         if (builtInOtel != null) {
           recorders.add(
               new OpenTelemetryMetricsRecorder(builtInOtel, TelemetryConstants.METRIC_PREFIX));

java-datastore/google-cloud-datastore/src/main/java/com/google/cloud/datastore/telemetry/OpenTelemetryMetricsRecorder.java

@@ -56,7 +56,7 @@ class OpenTelemetryMetricsRecorder implements MetricsRecorder {
   OpenTelemetryMetricsRecorder(@Nonnull OpenTelemetry openTelemetry, String metricPrefix) {
     this.openTelemetry = openTelemetry;
 
-    Meter meter = openTelemetry.getMeter(TelemetryConstants.METER_NAME);
+    Meter meter = openTelemetry.getMeter(metricPrefix);
 
     this.transactionLatency =
         meter

java-datastore/google-cloud-datastore/src/test/java/com/google/cloud/datastore/telemetry/MetricsRecorderTest.java

@@ -69,6 +69,22 @@ public void tracingEnabledButMetricsDisabledAndBuiltInDisabled_returnsNoOp() {
     assertThat(recorder).isInstanceOf(NoOpMetricsRecorder.class);
   }
 
+  @Test
+  public void defaultOptionsWithBuiltInMetricsEnabled_returnsOpenTelemetryRecorder() {
+    // By default, export of built-in metrics is enabled
+    DatastoreOptions options = baseOptions().build();
+    MetricsRecorder recorder = MetricsRecorder.getInstance(options);
+
+    // If we're not in an emulator, it should return an OpenTelemetryMetricsRecorder
+    // (Note: System.getenv() is hard to mock, but we assume it's not set in test environment)
+    String emulatorHost = System.getenv(DatastoreOptions.LOCAL_HOST_ENV_VAR);
+    if (emulatorHost == null || emulatorHost.isEmpty()) {
+      assertThat(recorder).isInstanceOf(OpenTelemetryMetricsRecorder.class);
+    } else {
+      assertThat(recorder).isInstanceOf(NoOpMetricsRecorder.class);
+    }
+  }
+
   @Test
   public void openTelemetryRecorderCreatedWithExplicitOpenTelemetry() {
     InMemoryMetricReader metricReader = InMemoryMetricReader.create();