fix: uses old version of gax-grpc method (#426)

Internally, we are using version 1.47.1 of the gax-grpc library, which does not provide a method currently being used (setExecutor).

In here we use a method that is available in 1.47.1 and achieves the same goal (setExecutorProvider).

Author: thiagotnunes

google-cloud-spanner/src/main/java/com/google/cloud/spanner/spi/v1/GapicSpannerRpc.java

@@ -60,7 +60,6 @@
 import com.google.cloud.spanner.admin.instance.v1.stub.GrpcInstanceAdminStub;
 import com.google.cloud.spanner.admin.instance.v1.stub.InstanceAdminStub;
 import com.google.cloud.spanner.admin.instance.v1.stub.InstanceAdminStubSettings;
-import com.google.cloud.spanner.spi.v1.SpannerRpc.Option;
 import com.google.cloud.spanner.v1.stub.GrpcSpannerStub;
 import com.google.cloud.spanner.v1.stub.SpannerStub;
 import com.google.cloud.spanner.v1.stub.SpannerStubSettings;
@@ -171,11 +170,13 @@
 /** Implementation of Cloud Spanner remote calls using Gapic libraries. */
 @InternalApi
 public class GapicSpannerRpc implements SpannerRpc {
+
   /**
    * {@link ExecutorProvider} that keeps track of the executors that are created and shuts these
    * down when the {@link SpannerRpc} is closed.
    */
   private static final class ManagedInstantiatingExecutorProvider implements ExecutorProvider {
+
     // 4 Gapic clients * 4 channels per client.
     private static final int DEFAULT_MIN_THREAD_COUNT = 16;
     private final List<ScheduledExecutorService> executors = new LinkedList<>();
@@ -317,7 +318,11 @@ public GapicSpannerRpc(final SpannerOptions options) {
             .setMaxInboundMessageSize(MAX_MESSAGE_SIZE)
             .setMaxInboundMetadataSize(MAX_METADATA_SIZE)
             .setPoolSize(options.getNumChannels())
-            .setExecutor(executorProvider.getExecutor())
+
+            // Before updating this method to setExecutor, please verify with a code owner on
+            // the lowest version of gax-grpc that needs to be supported. Currently v1.47.17,
+            // which doesn't support the setExecutor variant.
+            .setExecutorProvider(executorProvider)
 
             // Set a keepalive time of 120 seconds to help long running
             // commit GRPC calls succeed
@@ -480,6 +485,7 @@ private static void checkEmulatorConnection(
 
   private static final class OperationFutureRetryAlgorithm<ResultT, MetadataT>
       implements ResultRetryAlgorithm<OperationFuture<ResultT, MetadataT>> {
+
     private static final ImmutableList<StatusCode.Code> RETRYABLE_CODES =
         ImmutableList.of(StatusCode.Code.DEADLINE_EXCEEDED, StatusCode.Code.UNAVAILABLE);
 
@@ -519,6 +525,7 @@ public boolean shouldRetry(
 
   private final class OperationFutureCallable<RequestT, ResponseT, MetadataT extends Message>
       implements Callable<OperationFuture<ResponseT, MetadataT>> {
+
     final OperationCallable<RequestT, ResponseT, MetadataT> operationCallable;
     final RequestT initialRequest;
     final MethodDescriptor<RequestT, Operation> method;
@@ -575,6 +582,7 @@ public OperationFuture<ResponseT, MetadataT> call() throws Exception {
   }
 
   private interface OperationsLister {
+
     Paginated<Operation> listOperations(String nextPageToken);
   }
 
@@ -610,6 +618,7 @@ private Operation mostRecentOperation(
   }
 
   private static final class TimestampComparator implements Comparator<Timestamp> {
+
     private static final TimestampComparator INSTANCE = new TimestampComparator();
 
     @Override
@@ -1458,6 +1467,7 @@ public boolean isClosed() {
    * the {@link ResultStreamConsumer}.
    */
   private static class SpannerResponseObserver implements ResponseObserver<PartialResultSet> {
+
     private StreamController controller;
     private final ResultStreamConsumer consumer;