chore(deps): Update gapic-generator-java to 2.15.3 (#1019)

* chore(deps): Update gapic-generator-java to 2.15.3

PiperOrigin-RevId: 516900470

Source-Link: googleapis/googleapis@42ba7e6

Source-Link: https://github.com/googleapis/googleapis-gen/commit/21abfad42a1f2edae64130bbf897283221cd66d7
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiMjFhYmZhZDQyYTFmMmVkYWU2NDEzMGJiZjg5NzI4MzIyMWNkNjZkNyJ9

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

google-cloud-datastore/src/main/java/com/google/cloud/datastore/admin/v1/stub/HttpJsonDatastoreAdminStub.java

@@ -18,6 +18,7 @@
 
 import static com.google.cloud.datastore.admin.v1.DatastoreAdminClient.ListIndexesPagedResponse;
 
+import com.google.api.HttpRule;
 import com.google.api.core.BetaApi;
 import com.google.api.core.InternalApi;
 import com.google.api.gax.core.BackgroundResource;
@@ -33,6 +34,7 @@
 import com.google.api.gax.rpc.ClientContext;
 import com.google.api.gax.rpc.OperationCallable;
 import com.google.api.gax.rpc.UnaryCallable;
+import com.google.common.collect.ImmutableMap;
 import com.google.datastore.admin.v1.CreateIndexRequest;
 import com.google.datastore.admin.v1.DeleteIndexRequest;
 import com.google.datastore.admin.v1.ExportEntitiesMetadata;
@@ -365,7 +367,26 @@ protected HttpJsonDatastoreAdminStub(
       throws IOException {
     this.callableFactory = callableFactory;
     this.httpJsonOperationsStub =
-        HttpJsonOperationsStub.create(clientContext, callableFactory, typeRegistry);
+        HttpJsonOperationsStub.create(
+            clientContext,
+            callableFactory,
+            typeRegistry,
+            ImmutableMap.<String, HttpRule>builder()
+                .put(
+                    "google.longrunning.Operations.CancelOperation",
+                    HttpRule.newBuilder()
+                        .setPost("/v1/{name=projects/*/operations/*}:cancel")
+                        .build())
+                .put(
+                    "google.longrunning.Operations.DeleteOperation",
+                    HttpRule.newBuilder().setDelete("/v1/{name=projects/*/operations/*}").build())
+                .put(
+                    "google.longrunning.Operations.GetOperation",
+                    HttpRule.newBuilder().setGet("/v1/{name=projects/*/operations/*}").build())
+                .put(
+                    "google.longrunning.Operations.ListOperations",
+                    HttpRule.newBuilder().setGet("/v1/{name=projects/*}/operations").build())
+                .build());
 
     HttpJsonCallSettings<ExportEntitiesRequest, Operation> exportEntitiesTransportSettings =
         HttpJsonCallSettings.<ExportEntitiesRequest, Operation>newBuilder()