fix(datastore): Configure TraceExporter with Datastore credentials in E2E tests (#13627)

Fixes #13618

Configure `TraceExporter` and `TraceServiceClient` with default
Datastore credentials in `ITE2ETracingTest`. This fixes authentication
issues when running E2E tracing tests in environments where Application
Default Credentials (ADC) might not be automatically picked up by the
exporter or client.

Similar to the fix implemented for Spanner in
ef76d87.

TAG=agy
CONV=5d4f613d-13e3-4d5f-aa1f-5a913b05c507

Author: lqiu96

java-datastore/google-cloud-datastore/src/test/java/com/google/cloud/datastore/it/ITE2ETracingTest.java

@@ -37,8 +37,10 @@
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
+import com.google.api.gax.core.FixedCredentialsProvider;
 import com.google.api.gax.rpc.DeadlineExceededException;
 import com.google.api.gax.rpc.NotFoundException;
+import com.google.auth.Credentials;
 import com.google.cloud.datastore.AggregationQuery;
 import com.google.cloud.datastore.AggregationResult;
 import com.google.cloud.datastore.AggregationResults;
@@ -58,6 +60,7 @@
 import com.google.cloud.opentelemetry.trace.TraceConfiguration;
 import com.google.cloud.opentelemetry.trace.TraceExporter;
 import com.google.cloud.trace.v1.TraceServiceClient;
+import com.google.cloud.trace.v1.TraceServiceSettings;
 import com.google.common.base.Preconditions;
 import com.google.devtools.cloudtrace.v1.Trace;
 import com.google.devtools.cloudtrace.v1.TraceSpan;
@@ -246,12 +249,12 @@ private boolean dfsContainsCallStack(long spanId, List<String> expectedCallStack
   private static TraceExporter traceExporter;
 
   // Required for reading back traces from Cloud Trace for validation
-  private static TraceServiceClient traceClient_v1;
+  private static TraceServiceClient traceClient;
 
   // Custom SpanContext for each test, required for TraceID injection
   private static SpanContext customSpanContext;
 
-  // Trace read back from Cloud Trace using traceClient_v1 for verification
+  // Trace read back from Cloud Trace using traceClient for verification
   private static Trace retrievedTrace;
 
   private static String rootSpanName;
@@ -280,10 +283,24 @@ private boolean dfsContainsCallStack(long spanId, List<String> expectedCallStack
   @BeforeClass
   public static void setup() throws IOException {
     projectId = DatastoreOptions.getDefaultProjectId();
-    traceExporter =
-        TraceExporter.createWithConfiguration(
-            TraceConfiguration.builder().setProjectId(projectId).build());
-    traceClient_v1 = TraceServiceClient.create();
+
+    // Share the same credentials used by Datastore client with the TraceExporter and
+    // TraceServiceClient to ensure consistency and avoid auth issues in environments
+    // where default ADC resolution might fail for the exporter.
+    Credentials credentials = DatastoreOptions.getDefaultInstance().getCredentials();
+
+    TraceConfiguration.Builder traceConfigurationBuilder =
+        TraceConfiguration.builder().setProjectId(projectId);
+    if (credentials != null) {
+      traceConfigurationBuilder.setCredentials(credentials);
+    }
+    traceExporter = TraceExporter.createWithConfiguration(traceConfigurationBuilder.build());
+
+    TraceServiceSettings.Builder clientBuilder = TraceServiceSettings.newBuilder();
+    if (credentials != null) {
+      clientBuilder.setCredentialsProvider(FixedCredentialsProvider.create(credentials));
+    }
+    traceClient = TraceServiceClient.create(clientBuilder.build());
     random = new Random();
   }
 
@@ -381,7 +398,7 @@ public void after() throws Exception {
 
   @AfterClass
   public static void teardown() throws Exception {
-    traceClient_v1.close();
+    traceClient.close();
   }
 
   // Generates a random hex string of length `numBytes`
@@ -443,7 +460,7 @@ protected void fetchAndValidateTrace(
     // Fetch traces
     do {
       try {
-        retrievedTrace = traceClient_v1.getTrace(projectId, traceId);
+        retrievedTrace = traceClient.getTrace(projectId, traceId);
         assertEquals(traceId, retrievedTrace.getTraceId());
 
         logger.info(
@@ -530,7 +547,7 @@ public void traceContainerTest() throws Exception {
     int numRetries = GET_TRACE_RETRY_COUNT;
     do {
       try {
-        traceResp = traceClient_v1.getTrace(projectId, customSpanContext.getTraceId());
+        traceResp = traceClient.getTrace(projectId, customSpanContext.getTraceId());
         if (traceResp.getSpansCount() == expectedSpanCount) {
           logger.info("Success: Got " + expectedSpanCount + " spans.");
           break;
@@ -990,7 +1007,7 @@ public void runInTransactionQueryTest() throws Exception {
           Query.newEntityQueryBuilder().setKind(KEY1.getKind()).setFilter(filter).build();
       Datastore.TransactionCallable<Boolean> callable =
           transaction -> {
-            QueryResults<Entity> queryResults = datastore.run(query);
+            QueryResults<Entity> queryResults = transaction.run(query);
             assertTrue(queryResults.hasNext());
             assertEquals(entity1, queryResults.next());
             assertFalse(queryResults.hasNext());
@@ -1007,7 +1024,7 @@ public void runInTransactionQueryTest() throws Exception {
         /* numExpectedSpans= */ 4,
         Arrays.asList(
             Arrays.asList(SPAN_NAME_TRANSACTION_RUN, SPAN_NAME_BEGIN_TRANSACTION),
-            Arrays.asList(SPAN_NAME_TRANSACTION_RUN, SPAN_NAME_RUN_QUERY),
+            Arrays.asList(SPAN_NAME_TRANSACTION_RUN, SPAN_NAME_TRANSACTION_RUN_QUERY),
             Arrays.asList(SPAN_NAME_TRANSACTION_RUN, SPAN_NAME_TRANSACTION_COMMIT)));
   }
 }