chore: Remove credential hashing from MetricServiceClient cache key

Author: lqiu96

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

@@ -85,12 +85,10 @@ static class CachedMetricsClient {
   }
 
   /**
-   * Shared cache for {@link MetricServiceClient} instances, keyed by
-   * "projectId:databaseId:credentialsHashCode". Sharing a single gRPC channel across exporter
-   * instances that target the same project, database, and credentials avoids per-client channel
-   * overhead (threads, connections, memory). The credentials hash ensures that clients using
-   * different credentials get their own isolated channel. Reference counting is used to safely shut
-   * down the client when no longer needed.
+   * Shared cache for {@link MetricServiceClient} instances, keyed by "projectId:databaseId".
+   * Sharing a single gRPC channel across exporter instances that target the same project and
+   * database avoids per-client channel overhead (threads, connections, memory). Reference counting
+   * is used to safely shut down the client when no longer needed.
    */
   static final ConcurrentHashMap<String, CachedMetricsClient> METRICS_CLIENT_CACHE =
       new ConcurrentHashMap<>();
@@ -136,8 +134,7 @@ static DatastoreCloudMonitoringExporter create(
       String databaseId,
       Credentials credentials,
       Map<String, String> clientAttributes) {
-    int credHash = credentials != null ? credentials.hashCode() : 0;
-    String key = projectId + ":" + databaseId + ":" + credHash;
+    String key = projectId + ":" + databaseId;
 
     // Use compute to acquire or create the client atomically with reference counting.
     // If creation fails, we log the error and return null so it's not added to the map.

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

@@ -83,7 +83,7 @@ public void setUp() {
 
     exporter =
         new DatastoreCloudMonitoringExporter(
-            PROJECT_ID + ":" + DATABASE_ID + ":0",
+            PROJECT_ID + ":" + DATABASE_ID,
             PROJECT_ID,
             DATABASE_ID,
             fakeMetricServiceClient,
@@ -166,22 +166,24 @@ public void testClientCacheReferenceCounting() {
     EasyMock.expectLastCall(); // Expect shutdown when refCount reaches 0
     replay(mockClient);
 
-    String key = PROJECT_ID + ":" + DATABASE_ID + ":0";
+    String key = PROJECT_ID + ":" + DATABASE_ID;
     DatastoreCloudMonitoringExporter.CachedMetricsClient cachedMetricsClient =
         new DatastoreCloudMonitoringExporter.CachedMetricsClient(mockClient);
     cachedMetricsClient.refCount.set(2); // Simulate 2 references
     DatastoreCloudMonitoringExporter.METRICS_CLIENT_CACHE.put(key, cachedMetricsClient);
 
     DatastoreCloudMonitoringExporter exporter1 =
-        new DatastoreCloudMonitoringExporter(key, PROJECT_ID, DATABASE_ID, mockClient, Collections.emptyMap());
+        new DatastoreCloudMonitoringExporter(
+            key, PROJECT_ID, DATABASE_ID, mockClient, Collections.emptyMap());
 
     // First shutdown should decrement refCount to 1, but not close client
     exporter1.shutdown();
     assertThat(cachedMetricsClient.refCount.get()).isEqualTo(1);
     assertThat(DatastoreCloudMonitoringExporter.METRICS_CLIENT_CACHE.containsKey(key)).isTrue();
 
     DatastoreCloudMonitoringExporter exporter2 =
-        new DatastoreCloudMonitoringExporter(key, PROJECT_ID, DATABASE_ID, mockClient, Collections.emptyMap());
+        new DatastoreCloudMonitoringExporter(
+            key, PROJECT_ID, DATABASE_ID, mockClient, Collections.emptyMap());
 
     // Second shutdown should decrement refCount to 0, close client, and remove from cache
     exporter2.shutdown();