Stop referring to WorkQueue.Executor

Change-Id: Ic4b4003a78205f4e34d656f5462a529e536f0b5a
diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java b/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java
index 91fd4f0..bc2bb22 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java
@@ -66,6 +66,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.Callable;
+import java.util.concurrent.ScheduledThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 import org.apache.commons.io.FilenameUtils;
 import org.eclipse.jgit.lib.Constants;
@@ -87,7 +88,7 @@
   private final ProjectControl.Factory projectControlFactory;
   private final GitRepositoryManager gitManager;
   private final PermissionBackend permissionBackend;
-  private volatile WorkQueue.Executor pool;
+  private volatile ScheduledThreadPoolExecutor pool;
   private final PerThreadRequestScope.Scoper threadScoper;
   private final DestinationConfiguration config;
   private final DynamicItem<EventDispatcher> eventDispatcher;